This chapter teaches people to:
- Determine the type of garden that works best for a given environment and interests.
- Properly plan a vegetable garden.
- Prepare soil, plant, and care for a vegetable garden throughout the year.
- Identify and manage the major pests and diseases that affect vegetable crops.
- Understand the basics of culinary herb cultivation in the home garden.
Many gardeners grow vegetables for the outstanding flavor and freshness of homegrown produce or to reduce the family food budget. Others are inspired by the wide variety of options and easy access to hard-to-find and unusual varieties. For example, a grocery store may have only three types of squash, whereas a seed catalog may have 49 or more (Figure 16–1). Still others view vegetable gardening as a relaxing escape from everyday pressures. The food they produce may be secondary to the sense of joy and accomplishment they get from tending the garden and sharing produce with neighbors and friends.
Successful vegetable gardening begins with selecting a site, planning what to grow, and preparing the soil. Once the garden area is ready, vegetables are selected, planted, and nurtured until the produce is ready to harvest. Vegetable gardening can be accessible to anyone with a sunny space, some seeds, water, fertilizer, and patience (Figure 16–2).
A Vegetable Garden for Every Lifestyle
Before donning garden gloves and putting seeds in the soil, give careful thought to the type or types of vegetable gardens that work best for your lifestyle. Consider the size of your family, the vegetables you wish to grow, the health of the soil, and how much time and money you have to invest in a vegetable garden.
If you have a sunny backyard with space to spare and good quality soil, you have the option of planting a traditional in-ground vegetable garden. If your soil is poor, you may wish to consider planting in raised beds. Front yards are often overlooked—underused spaces that could provide food if located in a neighborhood with no restrictions. Many vegetable plants are beautiful. If your landscape is already well-established and you have no room for a traditional vegetable garden, interplanting vegetables in your ornamental beds is a great option. Interplanting is also an easy first step to try vegetable gardening if you are unsure about dedicating a new space to vegetables.
Many vegetables thrive in containers, and container gardening is ideal for those with limited outdoor space. Vegetables cannot survive indoors without supplemental light, but growing plants indoors hydroponically is an option that is gaining popularity (Figure 16–3). Hydroponics allows the gardener to control temperature, light, and nutrients, all without as many pathogen pressures as plants grown outdoors. It can involve a large initial investment, so it may not be the best choice for someone new to growing plants.
These methods are not mutually exclusive. For example, you could grow cucumbers and corn in a traditional in-ground garden bed in your backyard while growing carrots and broccoli in a raised bed in your front yard. At the same time, you could interplant a perennial border with kale and Swiss chard, grow herbs in containers on your back patio, and produce microgreens hydroponically inside your home.
Prior to selecting a site, consider previous uses of the land and potential contaminants. Review NC State Extension publication AGW-439-78, Soil Facts: Minimizing Risks of Soil Contaminants in Urban Gardens, which provides indicators for concern, guidelines for when to have the soil tested for contaminants, directions for how to interpret the results, and strategies for minimizing risks—for example, using raised beds with imported soil or containers.
The most important factor to consider when selecting a garden site is sunlight. The garden must receive at least 6 hours of direct sunlight each day; 8 to 10 hours is ideal. Vegetables should be planted away from the shade of buildings, and the shade and competing root systems of trees and shrubs. Some vegetables tolerate shade better than others. Those vegetables that produce edible stems and leaves (such as broccoli, cabbage, collards, kale, lettuce, parsley, and spinach) as well as those that produce edible roots (such as beets, carrots, radishes, and turnips) are more tolerant of shade. Plants that flower and set fruit, such as eggplants, melons, peppers, and tomatoes, require more light.
Good soil drainage is also very important. Observe your yard after a rain. Areas where water pools have poor drainage and without serious remediation would not be a good site for a garden (Figure 16–4). Chapter 1, “Soils and Plant Nutrients,” provides more information about the soil in your garden as well as soil testing. Learn about amending your soil in chapter 2, “Composting.” More about preparing garden soil is covered in the following sections.
Placing a garden near the home or near a pattern of foot traffic through the yard ensures easy access for garden tasks and facilitates frequent inspections. Consider convenient availability to clean water sources when locating your garden. Access to a hose bib or irrigation system saves the effort of hauling water during dry months.
Another important consideration is good air movement. Avoid locating the garden in a low spot, such as at the base of a hill. These areas are slow to warm in the spring, and frost forms more readily in them because cold air cannot drain away. Vegetable gardens located on high ground are more likely to escape light freezes, which may permit an earlier start in the spring and a longer harvest in the fall. If access to land is a problem, explore opportunities at a community garden. Visit the NC Community Gardens Directory for a list of active community gardens.
Garden Types and Techniques
There is a garden type, or a combination of types, to fit each gardener’s needs. Gardens can be grown in-ground, in a raised bed, or in containers. In addition, a variety of techniques can be used to manage the garden. Plants can be laid out in traditional rows or intensely planted, or can take advantage of vertical spaces. Review the following types and techniques, and select the strategies that work best for your unique situation.
In ground gardens are less expensive, the water does not drain away as quickly, and the roots stay cooler in the summer. While water does not drain as quickly from in-ground beds, it can be difficult to supply water only to planting beds and not to adjoining areas. An in-ground garden generally requires more space than raised bed or container gardens. Care must be taken to create paths for traffic to avoid compaction of planting areas. Weeds from adjacent pathways can be challenging to manage (Figure 16–5).
Raised Bed Gardens
Raised beds are garden spaces elevated 6 to 8 inches or more aboveground (Figure 16–6). They are connected to the native soil beneath them and they may or may not have constructed sides. They can simply consist of soil piled high with a flattened top, or they can be framed with logs or rocks, constructed out of lumber boards, or made of straw bales (Figure 16–7). Raised beds, arranged just wide enough to reach to the center, are ideal for growing vegetables. Having defined beds not only makes a garden attractive, it also limits foot traffic in the bed, which can compact soil. Soil raised aboveground will likely drain well and warm up earlier in the spring. Raised beds do require more frequent irrigation than those planted in a traditional in-ground garden. As a higher percentage of the available growing space is used, there is less room for weeds to grow and water can be used more efficiently. When planted properly, one 4-foot by 8-foot raised bed can supply the majority of produce during the growing season for one or two people. Raised beds are generally 8 to 12 inches high, 3 to 4 feet wide, and as long as desired or as dictated by the materials used.
If the raised bed has sides, they should be made of a rot-resistant material. Wood products can be naturally rot-resistant or can be comprised of wood shavings mixed with synthetic materials such as plastic. Naturally rot-resistant woods include Eastern red cedar (Juniperus virginiana), redwood (Sequoia sempervirens), and black locust (Robinia pseudoacacia).
Growing edibles in containers is a popular way to produce food for the home. Many vegetables can be grown in containers deep enough to support their roots (Figure 16–8). Container size is directly related to gardening ease and success—larger is better. Vegetables that thrive in containers include beans, beets, carrots, collards, cucumbers, eggplants, garlic, kale, leeks, lettuces, mustard greens, peas, peppers, potatoes, spinach, squash, Swiss chard, and tomatoes. Gardening in containers is particularly useful for people with limited space, soil problems, or heavy wildlife pressure. Containers can be placed on a rooftop, balcony, patio, deck, entrance area, or walkway. Containers should be placed in locations that favor the growth of the crop being grown. For instance, a container can be moved to a sunny spot if growing tomatoes, a partly shady area when growing lettuce, or a protected microclimate during the winter for growing year-round kale. Container gardening of edibles offers more flexibility than traditional gardening and is great for children, renters, new gardeners, people with physical limitations, or experienced gardeners wanting to downsize. With container gardening, there is no digging or tilling and crops are virtually weed-free. Container gardening can also be a way of containing aggressive herbs, such as mint, that may otherwise take over traditional garden spaces. Vegetables grown in containers do require more care than plants grown in traditional garden beds in the ground. Learn more about growing edibles in containers in chapter 18, “Plants Grown in Containers.”
Single-row planting started when mules were used to cultivate the garden. Out of habit, many gardeners still use this system for in-ground, and even some raised beds. If space is not an issue, a traditional row garden is an option. Row gardens allow for the use of a tractor and tiller for garden chores (Figure 16–10). Create planting “beds” with rows planted close together, or use wide rows to shade out weeds.
If you are making traditional garden rows, make them straight to aid in cultivation, weed management, and harvesting. In traditional beds with rows, the entire garden is amended—both the rows and the pathways. To make a straight row, drive a stake into the ground at each end of the row and draw a string taut between the stakes.
The purpose of an intensively grown garden is to harvest the most produce possible from a given space. Intensive gardening has become a popular model as urban areas have become more crowded and yards have become smaller. Many home landscapes cannot accommodate the traditional row garden, and intensive gardening provides a viable alternative. Intensive gardens optimize the use of space and use succession planting to maximize production, but they require careful planning. Although intensive gardens are often in raised beds, they can also be in-ground gardens or even in large containers (see Table 16–1 for recommended spacing in intensive gardening).
One method of intensive planting is “square foot gardening,” an approach that was formalized by Mel Bartholemew in his 1981 book Square Foot Gardening and his subsequent 2006 All New Square Foot Gardening. The French were using these intensive gardening techniques in the late 1800s, but Bartholemew popularized the concept. Vegetables are grown in 1-foot by 1-foot squares within a raised bed (Figure 16–11). Beds are designed to be no more than 4 feet across so they can be managed from the outside. The gardener never compacts the soil by stepping where the vegetables grow. Gardeners can arrange their square-foot beds in multiple ways to fit the available space. Beds are marked in 1-foot squares using a wood lattice, string, plastic tape, or re-used slats from window blinds. These markings help clearly define planting spaces and make it easy to follow planting density recommendations. Within each square, many vegetables can be grown. The spacing is determined by the ultimate size of the vegetables grown within that square. Large plants, such as broccoli or tomatoes, may require multiple squares to allow each plant to grow to full size. Smaller plants (like beets) can be planted up to 16 plants per square, while others (such as carrots) can have 32 per square.
Unlike in traditional row gardens, where there is generally as much empty space as plant-occupied space, no wasted space occurs within a square-foot garden. In intensive gardens, the fertilization, watering, and management efforts are concentrated on the planting beds. See Table 16–1.
Another method of intensive gardening is interplanting, or growing two or more types of vegetables in the same place at the same time (Figure 16–12). This technique has been practiced for thousands of years by American Indians, but is now regaining widespread support in this country. The benefits include increased production and a decrease in weeds. Proper planning is essential to obtain high production and improved quality of the crops planted. Another type of interplanting is to grow flowers among vegetable plants. This brings insect pollinators and predators, may deter pests, and adds color to a vegetable garden (Figure 16–13).
The following factors must be considered for each plant combination:
- The length and pattern of growth. Is the vegetable tall, short, belowground, or aboveground?
- Allelopathy or the possible negative effects of one crop on another. Some plants, such as sunflowers, produce toxins that impede the growth of other crops.
- The length to maturity. Mixing up maturity dates helps to extend harvesting.
- Light, nutrient, and moisture requirements of the plants. Using plants with like cultural requirements promoates optimal health of all the crops.
Possible plant combinations include planting long-season, slow-maturing plants and short-season, quick-maturing ones at the same time. An example of this combination would be peppers and radishes. The radishes are harvested before they begin to be crowded by the peppers. Another example of combining growth patterns is planting smaller plants close to larger plants, such as radishes at the base of beans or broccoli. Shade-tolerant species, such as lettuce, spinach, and celery, can be planted in the shadow of taller crops, like beans or squash.
Interplanting can be accomplished by alternating rows within a bed (plant a row of peppers next to a row of onions), by mixing plants within a row (leeks and parsley), by distributing various species throughout the bed, or by planting edibles among ornamentals. Swiss chard could be planted between azalea shrubs, or carrots could pop up along a walkway between perennial beds.
Distance (inches) Between Plants
The use of trellises, nets, strings, cages, or poles to support growing plants constitutes vertical gardening (Figure 16–14). This technique is especially suited to gardeners with only a small garden space. Vining and sprawling plants, including cucumbers, tomatoes, melons, and pole beans, are obvious candidates for this type of gardening. Some plants twine themselves onto the support; others require tying.
Vertical plantings cast a shadow, so place them on the north side of a garden bed to reduce shading, and plant shade-tolerant crops near the vertical ones. Plants grown vertically take up much less ground, and though the yield per plant may be less, the yield per square foot is much greater. Because vertically growing plants are more exposed, they dry out faster and require more water than if they were spread over the ground. This fast drying is advantageous to plants susceptible to fungal diseases. Vertical gardening is often used with raised beds.
In summary, any of these garden types and techniques can be used in isolation or combined to create a garden that works best for a given space. A raised bed can be planted intensively, or a container garden may use vertical gardening to its advantage. Whichever garden type or combination of types and techniques you choose, remember to start small, select plants appropriate for the season, that thrive in the light you have, make amendments to the soil based on your soil test report, manage the weeds and diseases, and only plant what you can manage easily and joyfully. As your interests and skills expand, so can your garden space.
How to Organize the Garden
Once you have decided on the space and the type of garden that best suits your needs, a diagram helps you organize the garden. There are several things to consider when creating a garden diagram.
- Use graph paper or a scale so you can accurately draw the size of the garden bed and plants.
- Draw a north arrow and make note of the sun’s pattern throughout the day.
- Note water access and composting locations.
- Use a different color or shape for each type of vegetable.
- Review planting dates of each crop to help you plan for succession throughout the growing season (see Table 16–2 for an example of succession planting). Ideally, once a crop has been harvested, another crop is ready to be planted in its place.
- Plant north to south to make the best use of sunlight.
- Group tall crops (corn, okra, sunflowers) and trellised vines (peas, beans, squash) together on the north side of the garden to avoid shading shorter plants. Follow this principle unless you are planting crops that are marginal in the summer, like lettuce, that can take advantage of the shade.
- Leave pathways so you can easily access the plants or beds from multiple sides.
- Show the plant size at maturity to ensure adequate space is allotted.
What to Plant
The simple answer to that question is this: “Grow what your family likes to eat and what you have space for.” Consult your garden plan. If you are planting in a limited space, consider vegetables that give the highest yield for the least amount of space, such as leafy greens, root crops, pole beans, and tomatoes. If you have plenty of square footage in your garden, you can plant crops like pumpkin, squash, and corn. If you are an adventurous chef, try planting vegetables that are unusual or expensive to buy at the market, such as broccolini, kale sprouts, or shallots. If your family hates zucchini, by all means, avoid planting any.
Be sure to consider the growing season when deciding what to plant. What to plant is infulenced by when you plant and vice versa. Most vegetables are annuals and reach maturity in one growing season. They are grouped according to the season that best meets their growth requirements. Spring and fall have short, cool days, so vegetables that do best during these times are called “cool-season annuals.” Summer is hot with long days, and vegetables that do best during this season are called “warm-season annuals.” Cool-season annuals include beets, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, collards, kale, kohlrabi, lettuce, mustard, onions, peas, potatoes, radishes, rutabagas, spinach, Swiss chard, and turnips. These vegetables grow well and produce leaves and roots in the cool temperatures of early spring and fall. Some cool-season annuals can be planted in the late summer and if they are well established, can survive the winter and continue growing again in the early spring. Warm-season annuals include beans, corn, cucumber, eggplant, melons, peppers, squash, sweet potatoes, and tomatoes. These vegetables grow best when the weather and soils warm up in the late spring and summer. Warm-season vegetables are generally not planted in the ground until after the last frost date. Check the days until fruit production and maturity on each variety you select. It may be necessary to plant starts instead of seeds, or start seeds early in a greenhouse, to get the highest yield. Some crops live for more than one season or year.
Biennial crops, such as artichokes and parsley, grow in the first year, and flower, fruit, and die in the second year.
When to Plant
With proper planning, your vegetable garden can provide produce almost year-round. Keeping track of planting and harvest dates, however, can be a challenge without an effective system. Writing planting and harvest dates on a calendar is a tactic many farmers and gardeners use. If you have a garden diagram, adding planting and harvesting dates can make it an even more powerful tool. By careful planning, even a small space can realize its full potential for vegetable production.
Spring. Cool-season annuals are cold-hardy plants that thrive in the early spring and fall when temperatures fall below 70°F. To get a jumpstart on the spring season, use a cold frame, low tunnel, or frost cloth. Warm-season annuals are frost-sensitive crops that grow well in the late spring when temperatures are above 70°F and soils have warmed up.
Summer. As temperatures rise, cool-season crops bolt and become bitter. Use shade cloth or taller crops to provide shade and extend cool-season crops into summer. Warm-season crops planted in late spring grow until the first frost. Late summer is the time to plant cool-season annuals for a fall harvest.
Fall. Cool-season annuals that are well-established grow through cold temperatures and sometimes even moderate freezing.
Winter. Crops considered cold hardy (such as collards, kale, turnip greens, spinach, and Swiss chard) planted in fall may live through the winter or may go dormant for a period in the winter and flourish again in early spring. A cold frame or frost cloth can help protect and extend this growing season. Many of these plants bolt quickly in the spring.
For specific planting dates, consult the North Carolina Planting Calendar for Vegetables, Fruits, and Herbs. To help extend the garden season, see Appendix E.
Succession planting is a technique in which vegetables are planted at staggered intervals to extend the harvest. If you want to have a huge harvest of tomatoes all at once so you can do all your canning in one weekend, this strategy is not for you. In addition to enabling an extended harvest, succession planting also buffers against total crop failure as another group of plants is in the queue. The easiest strategy for succession planting is to plant different varieties of the same vegetable that have different days to maturity. These crops naturally stagger their harvest times. The second strategy is to plant the same variety multiple times. The interval of time between planting should be as long as the harvest time for each particular vegetable. Filling in with a new vegetable in place of a vegetable that was harvested is also a way to make sure the garden stays in production for a longer period. When a head of lettuce is harvested in May, plant some carrots in the space that is made. If you remove a tomato plant because it has finished producing in the early fall, plant kale or rutabaga in its place to grow through the late fall and perhaps even overwinter. If you start some seeds in trays about four to five weeks ahead of the planned harvest schedule, you can get an even bigger jumpstart on your garden’s production. See Table 16–2.
To grow quality vegetables you need a soil that is fertile, deep, easily crumbled, well-drained, and high in organic matter. If you are gardening in containers, purchase potting soil or make your own mix by combining equal parts of compost, shredded pine bark, and vermiculite. Never use soil from your yard in containers. Using yard soil in a container will likely result in poor drainage and may introduce pathogens that thrive in an enclosed environment. For more about outdoor container gardening, read chapter 18, “Plants Grown in Containers.”
To plant in raised beds or in-ground gardens, start by amending the soil with 2 inches to 3 inches of homemade or certified compost. Then take a sample and submit it to the NC Department of Agriculture & Consumer Services (NCDA&CS) for a soil test. The soil test gives you information about the makeup of your soil (mineral or organic), the pH (acidity or alkalinity), the nutrient content, and the amounts of lime or fertilizer per 1,000 square feet of growing area that might be needed to correct pH or nutrient levels.
A soil test should be repeated every two to three years. The ideal pH range for most vegetables is between 6.0 and 6.5. If lime is needed, try to apply it several months before planting. Lime reacts relatively slowly in soil; therefore, a fall application of lime can correct soil acidity before spring planting. Read more about soils and soil testing in chapter 1, “Soils and Plant Nutrients.”
The fastest way to improve sandy soil or heavy clay soil is by repeatedly adding organic matter. You can incorporate a 2-inch to 3-inch layer of well-rotted leaves or compost in the spring before preparing the soil and again in the fall after harvest. Green manure crops—such as winter rye, ryegrass, or wheat—can be planted in the garden in the fall and turned under in the spring when growth is about knee-high. For best results, seed fall cover crops between September 15 and October 20 in the NC piedmont (one to two weeks later in the NC coastal plain, and one to two weeks earlier in the NC mountains). Cover crops are not limited to fall planting. Clover or buckwheat can be planted after harvesting early spring vegetables like lettuce or spinach and turned under in time to plant a frost-tolerant crop in the late summer. Seeding rates per 1,000 square feet for winter rye are 1 to 2 pounds, and for ryegrass and wheat, 3 to 4 pounds. Read more information about cover crops in “Organic Gardening,” chapter 17.
Apply fertilizer, if recommended by a soil test, shortly before or at planting time. The best way to fertilize a traditional row garden is to broadcast half to two-thirds of the total amount and apply the remainder by banding. To broadcast, spread the fertilizer over the top of the soil with a cyclone or drop spreader in an east-west and north-south movement with half of the broadcast amount in each direction. Then till the fertilizer into the soil to a depth of 3 to 4 inches. For banding, apply fertilizer in furrows 3 inches from the center of the row and slightly below the level of the seed (Figure 16–15). For raised beds, sprinkle fertilizer evenly over the bed and scratch or rake it in. Water the soil before planting.
Some garden vegetables, such as beans, cabbage, peppers, potatoes, squash, and sweet corn, need extra nitrogen applied to the soil in the form of a side-dressing to keep them growing rapidly and continuously. See the NCDA&CS publication Note 4: Fertilization of Lawns, Gardens, and Ornamentals for more information.
Side-dress individual plants or hills with 1 level tablespoon of a high nitrogen fertilizer per plant (Figure 16–16). For organic fertilizer alternatives and application rates, see chapter 17, “Organic Gardening.” For widely spaced plants, such as cucumbers or cantaloupe, place the side-dressing fertilizer in bands 6 inches from the plant's base. Vegetable plants should be side-dressed about midway through their maturity cycle, except when grown on sandy soils and during periods of excessive rainfall; these conditions require more frequent side-dressing applications. Crops such as tomatoes, eggplant, and okra require two or three side-dressings per season because of their long growth cycles. For more information on fertilization, refer to chapter 1, “Soils and Plant Nutrients."
The 25-foot by 42-foot garden below could produce the majority of the vegetables needed for canning, freezing, and fresh use for one year for a family of four. In most of the rows, as soon as one crop is harvested, another is planted so that two crops can be grown in succession during the growing season. Because sweet corn requires a large space, the overall yield from the garden would be higher if lima beans or snap beans were planted in place of corn. Find out more about yield amounts in the “When to Harvest” section of this chapter.
|Asparagus bed (November-March)||Asparagus bed (November-March)||42'|
|Asparagus bed (November-March)||Asparagus bed (November-March)|
|Sweet corn * (April 15)||Broccoli (March 1)|
|Sweet corn * (April 15)||Broccoli (March 1)|
|Sweet corn * (April 15)||Irish potatoes (March 1)|
|Sweet corn * (April 15)||Irish potatoes (March 1)|
|Pole beans (April 15)||Irish potatoes (March 1)|
|Pole beans (April 15)||English Peas (March 1)|
|Tomatoes (May 1)||Cabbage (March 1)|
|Okra (May 1)||
Beets (March 1)
Southern peas (May 15)
Mustard (September 1)
|Eggplant and Peppers (May 1)||
Radishes (March 1)
Southern peas (May)
Collards (August 1)
|Lima beans (May 1)||Leaf lettuce (March 1)|
|Summer squash (May 1)||Cucumber (May 1)|
|Summer squash (May 1)||Cantaloupe (May 1)|
25' × 42' = 1050 square feet with 3.0 feet between rows.
Old seeds bought on sale may not be a bargain because their germination rate may be reduced and the resulting seedlings can be weak and grow very slowly. Check the date stamped on the seed packet to make sure the seeds were produced for the current gardening year. Many vegetable seeds, however, are viable for three to five years if kept in a dark dry place that stays below 85°F. Seed packets can be a wealth of information, and it is worth becoming familiar with all of the information on the back (Figure 16–18).
Bulk vegetable seeds sold by the ounce or pound in garden centers and farm supply stores are shipped to the store in a container or bag with a date and germination rate label attached. Look for the information before making a purchase. Seeds with high germination rates should be the first choice.
Review the North Carolina Planting Calendar for information on the crops that are best started as seeds in the ground, rather than as transplants. To be successful with directly sowing seeds, the garden soil should contain enough moisture at seeding to initiate germination. If it does not, water the soil thoroughly (4 to 6 inches deep) and allow the surface to dry before seeding. If preferred, the open furrow can be watered directly before depositing the seeds in the soil and covering firmly with dry soil. In the spring when the soil is cool, vegetable seeds are much less likely to germinate if they are planted too deeply. As a general rule, in the spring and summer plant the seeds 1 to 2 times their greatest diameter; in fall plant them 1½ to 2 times deeper.
Small seeds like lettuce and carrot can be difficult to distribute thinly and evenly. To sow small seeds, tear off a corner of the seed packet, then move the packet along the furrow while tapping it with an index finger. You can also mix the seeds with dry sand or dry, pulverized soil to help with even distribution.
Seeds that are large enough to handle can be planted by hilling or by row planting (drilling). Hilling is placing several seeds in one spot at definite intervals. Squashes, pumpkins, and melons are often planted this way. Once the seeds germinate, the hills are thinned, leaving one or two plants per hill, depending on the vegetable. Drilling is spacing seeds more or less evenly down the row. Beans and peas are planted this way. Plant them closer than the desired final spacing because after germination, extra plants can be removed. Planting extra seeds compensates for poor germination and loss of seedlings to disease and insects. If seeds are one year old or older, plant them thicker than fresh seeds.
Once the seeds are placed, cover them with soil. Firm the soil, but do not pack it, around the seeds with the flat blade of the hoe or your hands. Be careful to plant seeds at the recommended depth; seeds covered with too much soil may rot before germinating or the seedling may use up all of its stored energy before it grows to the surface and can produce food by photosynthesizing. On the other hand, seeds planted too close to the surface may die from overheating or drought.
The formation of a hard layer, or crusting, of the soil's surface developing shortly after seeding can prevent seedlings from emerging. Heavy rains or use of overhead sprinklers may cause soil crusting. To avoid this problem, incorporate 2 to 4 inches of organic matter into the soil, cover the seeds with the newly amended soil, and use a soaker hose instead of an overhead sprinkler.
Seedlings may be referred to as starts, sets, or transplants. They are started in containers indoors or in a greenhouse (see Appendix E) and can help plants get a jumpstart on growth when weather outside is unfavorable.
Warm-season plants can be transplanted to the garden when the danger of frost has passed. Starting cool-season crops, like lettuce and spinach, from seed in a greenhouse can help them mature before high outdoor temperatures can cause bolting. See Table 16–3 for temperatures and times to germinate vegetable seeds for later planting outside. Chapter 13, “Propagation,” provides additional information on starting transplants from seed. The North Carolina Planting Calendar gives suggested outdoor planting dates, cultivars, and spacing distance between plants.
The most common vegetables bought as young plants for transplanting are broccoli, cabbage, cauliflower, celery, eggplant, lettuce, peppers, and tomatoes. If you buy vegetable transplants, larger and taller are not necessarily better. Tomato plants that have already started to flower are not optimal, because flowering places the plant under stress. Good-quality transplants are stocky and medium size with a healthy appearance and good green color (not too pale and not too dark), are free from insects and diseases, and have a well-developed root system (Figure 16–19). Allow the transplants to harden off gradually, acclimatizing them to the conditions in the garden prior to planting.
Before transplanting to the garden, make sure the soil has been prepared according to the directions above and determine that the timing is appropriate for the crop. To prevent wilting, try to transplant on a cloudy day or in early evening. Check the weather forecast for the days after you intend to plant to avoid conditions like extreme heat, heavy rain, or hail, that could harm new transplants (Figure 16–20). Handle the plants carefully to avoid disturbing the roots and bruising the stem.
For container-grown plants, dig a hole large enough to accommodate the container. Peat and other biodegradable pots can be set directly in the planting hole. Although the pots eventually disintegrate in the ground, remove any part that is above the ground as it may wick water away from the roots. For most vegetables, place the transplant in the ground at the same depth as it grew in the container. Tomato plants are exceptions: They do develop roots all along buried stem tissue, dramatically expanding their root system (Figure 16–21). Plant by removing all but the top three sets of leaves, laying them sideways in a 3-inch to 4-inch-deep trench and burying all but the leaves (Figure 16–22).
If cold or windy conditions threaten spring transplants, place row covers, boxes, baskets, plastic milk jugs, or flower pots over the new transplants. Try to keep the covers from touching the plants, and do not leave them over the plants longer than necessary. If it gets warm during the day, remove the covers to provide proper ventilation. Summer transplants may need protection from heat for several days after they have been planted. A piece of wood or cardboard stuck in the ground at a slant on the south side of a plant can serve as a sunshade. Irrigation also helps to lower the air and soil temperature.
|Vegetable||Optimum Temperature||Growing Time
|Day (°F)||Night (°F)|
Table 16–5. Effective crop rotation. By selecting plants from different families, you can avoid pathogen and pest buildup that can occur if the same type of plant is used in the same place year after year.
|PLANT FAMILY||VEGETABLES & COVER CROPS|
|Carrot, Parsley (Apiaceae)||Caraway, carrots, celery, chervil, cilantro, coriander, dill, fennel, parsley, parsnips|
|Composite, Sunflower (Asteraceae)||Artichoke, chamomile, chicory, dandelion, echinacea, endive, escarole, Jerusalem lettuce, radicchio, safflower, salsify, sunflowers, tarragon|
|Goosefoot (Chenopodiaceae)||Beets, spinach, sugar beets, Swiss chard|
|Grass (Poaceae)||Barley, corn, fescue, lemon grass, millet, oats, rice, rye, ryegrass, sorghum, sorghum-sudangrass, sugar cane, timothy, wheat|
|Knotweed (Polygonaceae)||Buckwheat, rhubarb|
|Legume, Pea (Fabaceae)||Alfalfa, bean, birdsfoot trefoil, black medic, clovers, cowpeas, edamame, fava beans, garbanzo bean, garden peas, green/string beans, hairy vetch, lentil, peanuts, southern peas, soybeans, vetches|
|Lily (Liliaceae)||Asparagus, chives, garlic, leeks, onions, shallot|
|Morning-glory (Convolvulaceae)||Sweet potatoes|
|Mustard (Brassicaceae)||Arugula, Bok choi, broccoli, broccoli raab, broccolini, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, cress, horseradish, kale, kohlrabi, mizuna, mustard, mustard greens, pak choi, radishes, rape, rutabagas, tatsoi, turnips, watercress|
|Nightshade (Solanaceae)||Eggplant, peppers (bell and chile), potatoes, tobacco, tomatillo, tomato|
|Squash, Gourd, Melon (Cucurbitaceae)||Cantaloupe, cucumber, gourd, luffa, muskmelon, pumpkin, squash (summer and winter), watermelon, zucchini|
Anytime seedlings grow too close together, thinning can benefit the plants selected to remain. Thinning is the process of reducing the number of seedlings in the soil or container media, giving those that remain more room to grow (Figure 16–23). If seeds are sown at the desired rate from the beginning, as with square foot gardening, thinning may not be necessary.
Thinning is a valuable practice for several reasons:
- It reduces competition among the seedlings for soil nutrients, sunlight, and water.
- It can reduce some early disease problems by providing better air circulation around the plants.
- It contributes to higher yields by giving plants the proper amount of space in which to flourish.
Leaf lettuce, beets, radishes, carrots, spinach, turnips, and other plants with small seeds are easily overplanted. Start thinning when the plants have one or two pairs of true leaves. Evening is a good time to thin because the remaining plants have the cool, dark night to recover from any disturbance. Pinch or cut out seedlings rather than pulling them out of the soil to avoid potentially damaging nearby root systems. The cut seedlings may be edible and tasty.
General Garden Care
On average, vegetable gardens need 1 inch of water per week; provide only what is not supplied by rain. Keep a rain gauge in the garden to track precipitation, and adjust your watering times accordingly. Water the soil, not the plant. Many diseases are spread by water splashing from the soil up on the leaves or from a diseased leaf to a healthy one. Organic mulches (straw, leaves, or compost) help conserve moisture and prevent splash.
When providing an inch of water to the garden, the goal is to wet the soil to a depth of 6 inches. After some experimenting it is easy to tell how long it takes for water to reach that depth. One way to check is to dig into the soil with a long trowel or shovel to see how far the water has penetrated into the root zone. Another way is to measure how long it takes to apply 1 inch of water (which can moisten the soil to 6 inches deep, depending on soil type) by placing small, straight-sided containers in a grid pattern over the area being watered. Check the containers every 30 minutes until they contain l inch of water. As a general guide, the average house spigot must be left running approximately l ½ to 2 hours to apply 1 inch of water to 1,000 square feet. Gardens with sandy soil must be watered more frequently than those with a high percentage of clay. Failure to provide adequate moisture stresses the plants and reduces yields. On the other hand, overwatering can lead to insect and disease problems, as well as wash nutrients away, converting a valuable garden resource into pollution in nearby streams.
From a water conservation perspective, the most efficient time to water plants is at night. During a hot, dry, summer, this may be ideal as night-time temperatures remain high. Cooler night temperatures in the spring or fall, however, can keep water from evaporating. The longer water stays on the leaves, the higher the likelihood of disease problems. If it is cool and wet enough for dew to form on plants, the best time to water is mid-morning after the dew has dried. Watering the soil directly instead of overhead not only promotes water conservation but also saves money on your water bill. Drip and trickle irrigation systems allow a gardener to irrigate slowly and efficiently. A soaker hose is the least expensive and easiest to use. It operates at low pressure and delivers small amounts of water to the soil very slowly. A full drip irrigation system provides water to individual plants and can be controlled by a timer. Gardeners can install these systems or hire a contractor. Periodically check the emitters to ensure all the heads are functioning properly.
A portable lawn sprinkler is also an option, but be sure to keep the application rate low enough that water does not run off the soil. Also make sure that the vegetable plants themselves do not interfere with the application pattern. Often this requires mounting the sprinkler on a small platform above the plants.
Avoid frequent shallow watering, which promotes the development of roots in the top 1 to 2 inches of soil rather than at a greater depth.
As you recall from chapter 6, “Weeds,” weeds compete for available soil nutrients, water, air and sunlight, and provide a home for insects and diseases. A steel hoe is one of the most effective weapons in fighting the war against weeds. When used regularly, it is effective and inexpensive. It is not possible, however, to control all weeds with a hoe alone. Weeds at the base of the plant should be pulled by hand rather than running the risk of damaging the roots (Figure 16–24). Do not allow weeds to become well-established before they are removed because pulling large weeds can damage the root system of vegetable plants. Mulch can significantly decrease the amount of hoeing needed.
Mulches help retain soil moisture and reduce weed growth. They fall into two categories—organic types that decompose naturally in the soil and inorganic types that do not decompose and, therefore, must be removed after serving their purpose.
Organic mulches are by far the most common. Typical examples are bark chips, compost, ground corncobs, chopped cornstalks, grass clippings, leaves, newspapers, peanut shells, pine needles, sawdust, and grain straw. Organic mulches conserve soil moisture and reduce the soil temperature by 8°F to l0°F during the summer. For this reason, they should not be used too early in the spring. If mulches are applied to cold garden soils, the soil warms up slowly, causing plant maturity to be delayed. After the soil warms in the spring, organic mulch may be applied to a depth of 2 to 4 inches around well-established plants. Be sure that there is adequate moisture in the soil before applying the mulch as dry mulch can pull moisture out of the soil.
Inorganic mulches, such as plastic sheeting that comes in good contact with the soil, can increase soil temperature early in the growing season and reduce the weed population by excluding light. Install plastic mulch after fertilization, but before planting, when the soil is neither too wet nor too dry. Bury the edges to prevent the wind from blowing it away (Figure 16–25). Make short slits in the material with a pocketknife when planting seeds or transplants. Black plastic, which can raise soil temperatures by 5°F to 6°F, is recommended for crops that produce fruit on the ground, such as melons, cucumbers, squash, and tomatoes, because diseases are reduced when plant foliage has no contact with the soil. Clear plastic allows sun rays to penetrate and can increase the soil temperature more than any other type of mulch—by 8°F to 14°F. Because light can penetrate clear plastic, it is possible for weeds to grow underneath if temperatures do not get high enough. Plastic mulches have hidden financial and labor costs. Plants mulched with plastic need supplemental water as roots do not receive water from rainfall, and irrigation needs to be monitored carefully. Plastic mulches degrade and should be removed and replaced regularly. Unintended environmental cost is disposal in a landfill.
Herbicides are chemicals that kill existing weeds or interrupt the germination. No single herbicide controls all weeds or can be safely used for all vegetable crops. It is difficult to apply relatively small amounts of the herbicide evenly to the garden surface. Miscalculation or faulty calibration of the application equipment can cause some areas of the garden to be treated with too much or too little herbicide, leading to growth problems for some vegetables. Consult “Weeds,” chapter 6 of this handbook, or the North Carolina Agricultural Chemicals Manual for more information.
Appendix D reviews tools that can be used while tending a garden.
Lance Cheung, USDA CC0
Pest and Disease Management
Integrated Pest Management in the vegetable garden involves the same practices we learned about in chapter 8, “IPM”:
- Cultural management. Practices include planting on the recommended dates, spacing plants properly, rotating crops, mulching, providing good soil fertility, and removing debris.
- Mechanical management. Uses strategies such as installing physical barriers like mulch or placing plastic collars to protect vegetable stems.
- Biological management. Practices include planting resistant vegetable cultivars or using natural predators for plant pathogens.
- Chemical management. Involves the use of herbicides and pesticides.
Many of the cultural practices that help prevent disease also discourage pest infestations. Interplanting can help keep insect and disease problems under control. Pests are usually crop-specific; they prefer vegetables from one plant family. Mixing plant families breaks up expanses of pest-preferred crops and confines early pest damage within a small area, thus allowing more time to manage the pests. Avoid overcrowding of vegetables, which decreases air movement and increases humidity, the perfect conditions for many diseases.
Because many insects and diseases have preferred host plants within the same plant family, crop rotation helps prevent the buildup of insects and disease problems. Table 16–5 provides information about which vegetables are related. Avoid planting related vegetables (same family) in the same location more often than once every three years. Rotation also keeps plants healthy and less prone to insect and disease problems by managing soil structure and fertility. Planting crop families with varying root depths helps keep soil structure loose. Plant families have different nutrient requirements, so a good plan would be planting legumes, which replace nitrogen in the soil through nitrogen-fixing bacteria in their roots, after a heavy nitrogen feeder like broccoli or cabbage. Leaving garden beds fallow or planting with a green manure for a season is another method for breaking an insect or disease cycle and a chance for soil nutrients to be replenished.
Insects and diseases can be more abundant and difficult to control in a fall garden. Most insect and disease problems result from a buildup of their populations during the previous spring and summer. Pests can be kept at tolerable levels by managing irrigation and fertilization to optimize plant health. Plants under stress are more susceptible to insect and disease development. Check the plants frequently for insect and disease damage. If sufficient damage is detected, use Integrated Pest Management strategies to manage the pest (see chapter 8, “IPM”).
As with most gardening practices, preventing insects from damaging crops is partly a matter of timing. Some of the most common vegetable insects are discussed in Appendix C-Diagnostic Tables. AG-295, Insect and Related Pests of Vegetables, and the NC State Vegetable Pathology Lab Disease Fact Sheets are other sources of information. Read more about "Diseases" in chapter 5 and "Insects" in chapter 4.
When to Harvest
Vegetable nutritional content, freshness, and flavor depend on the stage of maturity and time of day that vegetables are harvested. Overly mature vegetables are stringy and coarse. When possible, harvest vegetables during the cool part of the morning and process them as soon as possible.
Some guidelines for harvesting vegetable crops based on average yield expected per square foot are provided below.
Asparagus (0.08 to 0.1 pound). Harvest the spears when they are at least 6 to 8 inches tall by snapping or cutting them at ground level. Up to eight spears per plant may be harvested the second year after planting. A full harvest season lasts four to six weeks during the third growing season (Figure 16–26).
Beans, lima (0.08 to 0.17 pound shelled). Harvest when the pods first start to bulge with the enlarged seeds. Pods must still be green, not yellowish (Figure 16–27).
Beans, snap (0.38 to 0.6 pound). Begin harvesting before seeds develop in the pod (when pods are about the diameter of a pencil). Beans are ready to pick if they snap easily when bent in half (Figure 16–28).
Broccoli (0.33 to 0.5 pound). Harvest the dark-green, compact cluster or head (about 6 inches in diameter) while the buds are tight, before any yellow flowers appear. Smaller side shoots develop later, providing a continuous harvest (Figure 16–29).
Brussels sprouts (0.25 to 0.38 pound). Harvest the lower sprouts (small heads) when they are about 1 to 1½ inches in diameter by twisting them off. Remove lower leaves along the stem to hasten maturity (Figure 16–30).
Cabbage (0.5 to 0.75 pound). Harvest when the heads feel hard and solid (Figure 16–31).
Carrots (0.5 to 0.8 pound). Harvest when the roots are ¾-inch to 1 inch in diameter. The largest roots generally have the darkest tops. Mulched fall carrots can be left in the ground all winter and harvested as needed (Figure 16–32).
Cauliflower (0.33 to 0.5 pound). Exclude sunlight (blanch) when the curds, or heads, are 1 to 2 inches in diameter by loosely tying together the outer leaves above the curd with a string or rubber band. Some varieties are self-blanching. Harvest the curds when they are 4 to 6 inches in diameter but still compact, white, and smooth. The head should be ready 10 to 15 days after tying (Figure 16–33).
Collards (0.33 to .67 pound). Harvest older, lower leaves when they reach a length of 8 to 12 inches. New leaves grow as long as the central growing point remains, providing a continuous harvest. Whole plants may be harvested and cooked if desired (Figure 16–34).
Corn, sweet (n/a). Silks begin to turn brown and dry out as the ears mature. Check a few ears for maturity by opening the top of the ear and pressing a few kernels with a thumbnail. If the liquid exuded is milky, rather than clear, the ear is ready for harvest (Figure 16–35).
Cucumbers (0.2 to 0.5 pound). Harvest when the fruits are deep-green, before any yellow appears. The length should be 2 to 3 inches for sweet pickles, 5 to 6 inches for dill pickles, and 6 to 8 inches for slicing. Pick cucumbers four to five times per week to encourage continuous production. Mature cucumbers left on the vine stop production of new fruits (Figure 16–36).
Eggplant (0.33 to 0.5 pound). Harvest when the fruits are 3 to 5 inches in diameter and their color is a glossy purplish-black. (Lilac and white cultivars of eggplant are also available.) The fruit is getting too old when the color starts to dull or become bronzed. Because the stem is woody, cut—do not pull—the fruit from the plant. A short stem should remain on each fruit (Figure 16–37).
Kale (0.33 to 0.67 pound). Twist off the outer, older leaves when they reach a length of 8 to 10 inches and are medium-green in color. New leaves grow, providing a continuous harvest. Heavy, dark-green leaves are overly mature and are likely to be tough and bitter (Figure 16–38).
Kohlrabi (0.38 to 0.6 pound). Harvest when the bulb (the edible part) is 2 to 3 inches in diameter. Cut off the plant just below the bulb. Stems become woody if the bulb is left too long before harvest (Figure 16–39).
Lettuce (0.33 to 0.4 pound). Harvest the older, outer leaves from leaf lettuce as soon as they are 4 to 6 inches long. Harvest heading types when the heads are moderately firm and before seed stalks form (Figure 16–40).
Muskmelons (cantaloupe) (0.28 pound). Harvest when the stem slips easily from the fruit with a gentle tug. Other indicators of ripeness are that the netting on the skin becomes rounded and the flesh between the netting turns from green to tan (Figure 16–41).
Mustard (0.33 to 0.67 pound). Harvest the leaves and leaf stems when they are 6 to 8 inches long; new leaves provide a continuous harvest until they become strong in flavor and tough in texture from temperature extremes (Figure 16–42).
Okra (0.29 to 0.33 pound). Harvest young, tender pods when they are 2 to 3 inches long. Pick at least every other day during the peak growing season. Overly mature pods become woody and are too tough to eat (Figure 16–43).
Onions (0.5 to 0.8 pound). Harvest when the tops fall over and begin to turn yellow. Dig the onions and allow them to dry out in the open sun for a few days to toughen the skin. Then remove the dried soil by brushing the onions lightly. Cut off the stems, leaving 2 to 3 inches attached to the bulbs, and store them in a netted bag in a cool, dry place (Figure 16–44).
Peas, English and Southern (.07 to 0.13 and 0.13 to 0.2 pound). Edible-podded cultivars should be harvested when pods are well-rounded, but before seeds are more than half of their full size. Harvest shelling peas when the pods are well rounded and the seeds are fully developed but still fresh and bright-green. Pods are getting too old when they lose their brightness and turn light-green or yellowish-green (Figure 16–45 and 16–46).
Peppers (0.2 to 0.3 pound). Harvest sweet peppers when the fruits are firm, crisp, and full size. Green peppers turn red if left on the plant. Allow hot peppers to attain their bright color (color depends on variety) and full flavor while attached to the vine; cut and hang them to dry (if desired) (Figure 16–47).
Potatoes, Irish (0.33 to 0.6 pound). Harvest the tubers when the plants begin to yellow and die down. Store the tubers in a cool, high-humidity location with good ventilation. Avoid exposing the tubers to light. Greening, which denotes the presence of dangerous alkaloids, occurs even with small amounts of light (Figure 16–48).
Pumpkins (0.5 to 0.6 pound). Harvest pumpkins and winter squash before frost and after the vine dries, the fruit color darkens, and the skin surface resists puncture from a thumbnail. Avoid bruising or scratching the fruit while handling it. Leave a 3-inch to 4-inch portion of stem attached to the fruit and store in a cool, dry location with good ventilation (Figure 16–49).
Radishes (0.08 to 0.11 pound). Harvest when the roots are ½-inch to 1½ inches in diameter (Chinese radishes grow much larger). The shoulders of radish roots often appear through the soil surface when they are mature. If left in the ground too long, they become tough and woody (Figure 16–50).
Rutabagas (0.33 to 0.57 pound). Harvest when the roots are about 3 inches in diameter. Mulched roots may be left in the ground and used as needed (Figure 16–51).
Spinach (0.23 to 0.36 pound). Harvest by cutting all the leaves off at the base of the plant when they are 4 to 6 inches long. New leaves will grow, providing additional harvests (Figure 16–52).
Squash, summer (0.3 to 0.5 pound). Harvest when the fruit is soft, tender, and 6 to 8 inches long (3 to 4 inches across for patty pans). The skin color often changes to a dark, glossy green or yellow, depending on cultivar. Pick every two to three days to encourage production (Figure 16–53).
Sweet potatoes (0.25 to 0.33 pound). Harvest the roots when they are large enough for use and before frost. Avoid bruising or scratching during handling (damaged sweet potatoes rot easily in storage). Ideal storage conditions are a temperature of 55°F and a relative humidity of 85%. The basement or crawl space of a house may suffice (Figure 16–54).
Swiss chard (0.33 to 0.67 pound). Harvest by breaking off the developed outer leaves 1 inch above the soil. New leaves will grow, providing a continuous harvest (Figure 16–55).
Tomatoes (0.25 to 0.5 pound). Harvest the fruits at the most appealing ripeness stage, up to fully red (Figure 16–56). (There are some yellow, purple, pink, and green cultivars of tomatoes.) Flavor is best at room temperature, but ripe fruit may be held in the refrigerator at 45°F to 50°F for seven to 10 days.
Turnips (0.38 to 0.6 pound). Harvest the roots when they are 2 to 3 inches in diameter, but before heavy frosts occur in the fall. The tops may be used as greens when the leaves are 3 to 5 inches long (Figure 16–57).
Watermelons (0.17 pound). Ripe watermelons produce a dull thud rather than a sharp, metallic sound when thumped. Other ripeness indicators are a deep-yellow rather than white color where the melon touches the ground, brown tendrils on the stem near the fruit, and a rough, slightly ridged feel to the skin surface (Figure 16–58).
Your garden may be so prolific that your harvest produces more vegetables than can be eaten fresh (Figure 16–59). There are many options for using the produce, including canning, freezing, pickling, and drying. These practices allow you to eat from your garden all year. Learn more about preserving your harvest from NC State Extension— Family and Consumer Sciences.
Rob Ireton, Flickr CC BY 2.0
Ton Rulkens, Flickr CC BY-SA 2.0
Rob Bertholf CC BY 2.0
Alice Henneman, Flickr CC BY 2.0
Garrett Heath, Flickr CC BY 2.0
timlewisnm CC BY-SA 2.0
Joi Ito, Flickr CC BY 2.0
Nick Harris, Flickr CC BY-ND 2.0
Espring4224, Flickr CC BY 2.0
Jobelina, Flickr CC BY-ND 2.0
Liz West, Flickr CC BY 2.0
Anna Gregory, Flickr CC BY 2.0
USDA CC BY 2.0
Manjith Kainickara CC BY-ND 2.0
Ali Graney, Flickr CC BY 2.0
Herbs are plants that add interest and flavor to our foods and perfume our homes (Figure 16–61). Herbs are pest-resistant plants that are relatively easy to grow. If you are adding herbs to your garden, start with the herbs that are used the most. For example, choose basil, fennel, and oregano for Italian cooking; lavender and lemon verbena for making potpourri; or chamomile and mints to make teas.
Some of the herbs familiar to North Americans, such as bay laurel, dill, lavender, marjoram, oregano, rosemary, and thyme, are native to the Mediterranean region. These herbs grow best in soils with excellent drainage, bright sun, and moderate temperatures.
When growing herbs, follow these basic guidelines:
- Plant herbs in average garden soil with organic matter added to improve texture and drainage.
- Choose a site that receives at least 6 hours of direct sun each day.
- Avoid ground where water stands or runs during rains.
- Compensate for poor drainage with raised beds.
- Apply balanced fertilizers sparingly to leafy, fast-growing herbs. Heavy applications of fertilizer, especially those containing large amounts of nitrogen, may decrease the concentration of essential oils in the lush green growth.
Most herbs require little special care after being established. Plan an herb garden by grouping herbs according to light, irrigation, and soil requirements. Most herbs enjoy full sun, but a few tolerate shade. Herbs can be classified as either annual, biennial, or perennial. Be aware of the growth habits of the plants before purchasing them. Some herbs—such as anise, borage, caraway, chervil, coriander, dill, and fennel—should be direct-seeded because they do not transplant well. Other herbs, such as mints, oregano, rosemary, tarragon, and thyme, should be transplanted to ensure production of the right plant and to obtain desired growth the first year. Additional information on specific herbs can be found in the NC State Extension Gardener Plant Toolbox.
To conserve moisture and prevent splashing mud on the plants, mulch an herb garden after planting. If you are planting from seed, wait until germination and establishment of the plants and then mulch. Use 1 to 2 inches of organic material. Many growers mulch with hardwood bark or a mixture of bark and sawdust.
When grown outdoors and given ample air circulation, sunlight, and water drainage, herbs rarely suffer severe disease or insect damage. Natural predators and parasites usually keep mite and aphid populations low. Traditional pesticides are not labeled for use on culinary herbs, so rely on cultural, biological, and physical management techniques. Insecticidal soap is useful against severe outbreaks of aphids, mites, and whiteflies. Hand -pick larger pests such as beetles and caterpillars.
Growing a diverse group of herbs can be attractive. Herbs provide color, fragrance, and interest throughout the season, and they help to keep pest problems at a minimum.
Most herbs grow healthier and fuller if they are harvested frequently. The method of harvesting depends on which herbs and their use.
- Begin harvesting herb leaves when the plants are well-established, but before flowering to keep leaf production high
- Harvest up to three-quarters of the current season’s growth.
- Harvest early in the morning, after the dew dries but before the sun becomes hot.
- Herb flowers have their most intense oil concentration and flavor when harvested after flower buds appear but before they open.
- Herb flowers harvested to dry for craft purposes should be picked just before they are fully open.
- Annual herbs can be harvested until frost.
- Perennial herbs can be clipped until late August. Stop harvesting about one month before the frost date. Later pruning could encourage frost-tender growth.
- Harvest lavender flowers in early summer, and then shear the plants to half their height to encourage a second flowering period in the fall.
Case Study—Think IPM: Pole Bean Problems
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
|Artichokes, globe||T=1 year||30 in||E||E||E|
(Best grown in a pot
because plants can
|Tu=6-8 months||9-12 in||E||E||E|
|Asparagus||C=2 years||18 in||E||E||E||E||E||E|
|Beans, lima/bush||65-80||6 in||E||E||E||E||E||E||E|
|Beans, lima/pole||75-95||6 in||E||E||E||E||E|
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
|Beans, snap/bush||50-55||2 in||E||E||E||E||E||E||E||E||E||E||E|
|Beans, snap/pole||65-70||6 in||E||E||E||E||E||E||E||E||E||E||E||E||E|
|Broccoli||T= 70-80||18 in||E||E||E||E||E||E||E|
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
|Corn, sweet||85-90||12 in||E||E||E||E||E|
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
|Florence fennel||60-90||6-12 in||E||E||E||E||E||E||E||E|
|Kohlrabi||T=22-32 S=50-60||4 in||E||E||E||E||E||E||E||E||E||E||E||E|
|Lettuce, head||T=45-60 S=70-85||10 in||E||E||E||E||E||E||E||E||E||E|
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
|Pac choi, bok choy||
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
|Peas, dwarf/bush||54-60||4 in||E||E||E||E||E||E||E||E||E||E||E|
|Peas, vining||54-72||2-3 in||E||E||E||E||E||E||E||E||E||E|
|Peas, field/southern||55-65||4 in||E||E||E||E||E||E||E||E||E|
|Potatoes, Irish||Tu=95-120||10 in||E||E||E|
|Potatoes, sweet||T=95-125||10 in||E||E||E||E||E|
|Fruit, Herb, or Vegetable||Days to Harvest
(from seed unless
|Distance Between Plants
E= Eastern, P= Piedmont, W= Western
B = Bulbs; C = Crowns; S = Seeds; T = Transplants; Tu = Tubers
Acknowledgments: This publication is based on prior work by Charlotte Glen, Danny Lauderdale, Kerrie Roach, Donna Teasley, Debbie Roos, Doug Jones, Erv Evans, and Larry Bass. The authors would like to thank Jeanine Davis, Bill Jester, Issac Lewis, Jonathan Schultheis, Allan Thornton, Kathleen Moore, and Debra Ireland for their assistance with this publication.
Prepared by: Lucy K. Bradley, Extension Specialist, Urban Horticulture; Christopher C. Gunter, Extension Specialist, Vegetable Crop Production; Julieta T. Sherk, Assistant Professor; and Elizabeth A. Driscoll, Extension Associate
Rob Berholf CC BY 2.0
Frequently Asked Questions
1. My tomatoes, peppers, or melons have dry rotten spots on the ends.
Blossom-end rot occurs on tomatoes, peppers, squash, eggplant, and watermelons from a lack of calcium in the developing fruits. It can be caused by fluctuations in the soil moisture, rapid early-season growth followed by extended dry weather, excessive rain, excess soil salts caused by overfertilization (especially with high nitrogen fertilizers), and improper soil pH. Fungi or bacteria that invade the damaged tissue may cause moldy growths on the rotted area. The rotten area looks unsightly, but the rest of the fruit is edible. Applying preventive sprays of calcium chloride to the tomatoes is not very effective. To prevent the problem in the future, maintain an even moisture level by regular watering and using good mulch. Plant in well-drained soil and avoid using high nitrogen fertilizers. Do not cultivate deeply close to the plant. Test soil and use lime as recommended to bring the pH up to 6.5 to 6.8. Smaller-fruited varieties, such as cherry tomatoes, are less susceptible to blossom-end rot.
2. My tomatoes do not set fruit.
This may be due to extreme temperatures causing blossoms to drop without setting fruit. This occurs when nighttime temperatures fall below 55°F or stay above 70°F, or daytime temperatures rise above 90°F for extended periods. Recently, new "hot-set" varieties of tomatoes, such as Sun Leaper and Solar Set, have been developed that continue to set fruit at high temperatures. There could be other explanations.
- Does the plant get enough sun? Tomatoes need at least 6 hours of sunlight per day.
- If there is vigorous leafy growth but no fruit, there may be too much nitrogen in the soil, which stimulates leaf production at the expense of fruit formation.
- Drought also causes tomato plants to not set fruit, so make sure the tomato plant is getting 1 inch to 2 inches of water per week and is kept evenly moist.
3. Can my vegetables cross-pollinate each other?
Pollination is the transfer of pollen from the anther to the stigma (ovary) of a flower that results in seed and enlargement of the ovary producing a fruit. Cross-pollination is the transfer of pollen from a flower on one plant to a flower of another plant. Different varieties of the same vegetable can cross-pollinate (yellow and white corn) and some closely related species in the same family (squash and pumpkins), but not species in different families (corn and melons). Even if your pumpkin and squash or cantaloupe and Crenshaw did cross-pollinate, however, the fruit would still look the same. Only if the seeds from the fruit produced were saved and planted the next season would you possibly see differently colored or shaped fruit produced. There are some exceptions, such as planting hot and sweet peppers near each other. The gene for hotness is dominant, and insect cross-pollination can occur in peppers. Therefore, the seed produced in the current season’s sweet pepper may contain capsaicin, which causes heat, and your sweet pepper could taste hot. Corn kernels are seeds, and planting white and yellow corn near each other can result in cobs with mixed yellow and white kernels. Likewise, a supersweet corn planted near a traditional corn cultivar does not develop its sweet flavor.
4. Why is my broccoli, spinach, lettuce, or other cool-season crop flowering? Can I still eat it?
Cole crops or cold weather crops thrive in cooler temperatures. When the weather warms up in the spring, it can signal to cole crops that it is time to flower and reproduce. This rapid growth of flowering structures is often called bolting. While you can still eat plants that have bolted, they often contain a bitter sap that makes them unpalatable. Consider planting cole crops in the fall rather than the spring.
5. Why do my cucumbers taste bitter?
Cucumbers grown under environmental stress—such as a lack of water, uneven watering practices, high heat or cool conditions, wide temperature swings, low soil fertility, or low soil pH—produce increased levels of chemicals called cucurbitacins. These compounds are bitter and concentrated in the cucumber’s skin. Misshapen fruit from poor pollination can also be bitter. Bitterness also varies to some degree with the particular variety of cucumber grown. Overly mature or improperly stored cucumbers may also develop a mild bitterness.
6. My tomato starts from the nursery do not have many leaves on the lower stem, but they do have a few blossoms and one tiny tomato. How deep should I plant?
Good early root establishment makes for the most prolific tomato plants. Tomato plants can produce adventitious roots all along their stem (see Figure 16-21), so burying the plant up to the first set of leaves can allow the plant to produce the most roots. If your plant is more than 6 to 7 inches tall, the soil below that depth could be too cool to promote the best root growth. In this case, consider digging a shallow trench and laying the tomato plant on its side (see Figure 16–22). Gently bend up the tip of the plant so it is above the soil line and cover the rest of the stem. Any blossoms or fruits should be pinched off because they can take energy away from developing roots.
7. Why are my broccoli or cauliflower heads small? And why is my cauliflower turning green?
When small heads form on broccoli or cauliflower, the condition is called “buttoning.” Excessive cold, nutrient deficiency, or drought stress (usually soon after planting) can cause buttoning. Large transplants are much more susceptible to buttoning, so look for plants with no more than four to six leaves. Cauliflower heads begin to turn green because they are starting to photosynthesize due to light exposure. When your head is approximately 3 inches across, you can keep light off of it by pulling leaves up and tying them together. This is known as “blanching.” Be sure to check on your plant frequently. If you notice it starting to bolt or elongate, harvest the entire head immediately.
8. There is a little tomato growing on my potato plant. Did they cross-pollinate?
Potatoes, tomatoes, eggplants, and peppers are in the Solanaceae or nightshade family. This family is self-pollinating, so unlikely to cross-pollinate. What you are seeing is the true fruit of a potato, which contains many tiny seeds. Do not eat the fruit, which is poisonous.
9. My zucchini plant has only produced a couple of fruits this summer. What is wrong with it?
Zucchini are members of the cucurbits family, along with squash, melons, and cucumbers. Cucurbits produce separate male and female flowers. The male flowers produce large, sticky, yellow pollen that is not easily transferred by wind. The most effective pollinators for cucurbits are bees. Encourage native and honey bees in your yard by not spraying insecticides and by planting other nectar-producing plants. If you are in an urban area and have not seen many bees working your plants, try hand pollination. First distinguish male flowers from female flowers: Both have yellow petals, but female flowers have a tiny fruit at their base. Use an artist’s brush to collect some pollen from the stamen of a male plant, or remove the male flower, pull off the petals to expose the stamen, and place the pollen from the stamen or from your brush directly on the stigma of the female plant. It is best to try this technique early in the morning. It is important to use freshly opened flowers as they are only receptive for one day.
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Chapter Text Hyperlinks
NC Community Gardens Directory, North Carolina Community Garden Partners
Environmental Soil Issues: Garden Use of Treated Lumber, by PennStateExtension
NOTE 4: Fertilization of Lawns, Gardens and Ornamentals, NCDA&CS Agronomic Division
Home Food Preservation, NC State Extension, Family & Consumer Sciences
Kudzu Bug, by NC State Extension, Chatham County Center
For More Information
- Container Garden Planting Calendar for Edibles in the Piedmont
- Entomology Insect Notes, NC State University
- Extension Plant Pathology – Vegetables Website
- Extension Plant Pathology Facebook
- Fertilization of Lawns, Gardens and Ornamentals, NCDA&CS
- Herbicide Carryover in Hay, Manure, Compost, and Grass Clippings
- Home Food Preservation, NC State Extension, Family & Consumer Sciences
- Insect and Related Pests of Vegetables, AG-295
- Insects and Related Pests of Vegetables-Publications
- Local Food Information Portal
- North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs
- Plan for a Year-round Harvest, Carolina Farm Stewardship Association
- A Small Backyard Greenhouse for the Home Gardener
- SoilFacts: Minimizing Risks of Soil Contaminants in Urban Gardens, AG-439-78
- Vegetable Gardening: A Beginner's Guide
Author: Christopher Gunter, Associate Professor, Department of Horticultural Science
Contributions by Extension Agents: Lisa Rayburn, Donna Teasley, Julie Flowers, Danny Lauderdale, Silas Brown
Contributions by Extension Master Gardeners: Deborah Green, Margaret Genkins, Barbara Goodman, Jacquelyn Weedon, Karen Damari, Connie Schultz, Judith Bates, Chris Alberti, Brook Williams, Karen Jevsevar, Kim Curlee, Caro Dosé
Content Editors: Lucy Bradley, Extension Specialist, Urban Horticulture and Director of the Extension Master Gardener Volunteer program;
Kathleen Moore, Urban Horticulturist
Copy Editor: Barbara Scott, Debbi Braswell
Based in part on text from the 1998 Extension Master Gardener manual prepared by:
Larry Bass, Extension Specialist, Department of Horticultural Science
Erv Evans, Extension Associate, Department of Horticultural Science
Ken Sorensen, Extension Specialist, Department of Entomology
Doug Saunders, Extension Specialist, Department of Horticultural Science
Jeanine Davis, Extension Specialist, Department of Horticultural Science
Frank Louws, Extension Specialist, Department of Plant Pathology
How to cite this chapter:
Gunter, C. 2022. Vegetable Gardening, Chapter 16. In: K.A. Moore, and L.K. Bradley (eds). North Carolina Extension Gardener Handbook, 2nd ed. NC State Extension, Raleigh, NC. <http://content.ces.ncsu.edu/16-vegetable-gardening>
Publication date: Feb. 1, 2022
Other Publications in North Carolina Extension Gardener Handbook
- 1. Soils & Plant Nutrients
- 2. Composting
- 3. Botany
- 4. Insects
- 5. Diseases and Disorders
- 6. Weeds
- 7. Diagnostics
- 8. Integrated Pest Management (IPM)
- 9. Lawns
- 10. Herbaceous Ornamentals
- 11. Woody Ornamentals
- 12. Native Plants
- 13. Propagation
- 14. Small Fruits
- 15. Tree Fruit and Nuts
- 16. Vegetable Gardening
- 17. Organic Gardening
- 18. Plants Grown in Containers
- 19. Landscape Design
- 20. Wildlife
- 21. Youth, Community, and Therapeutic Gardening
- Appendix A. Garden Journaling
- Appendix B. Pesticides and Pesticide Safety
- Appendix C. Diagnostic Tables
- Appendix D. Garden Tools
- Appendix E. Season Extenders and Greenhouses
- Appendix F. History of Landscape Design
- Appendix G. Permaculture Design
- Appendix H. Community Gardening Resources
- Appendix I. More NC State Resources
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