Tomatoes are a favorite with home gardeners, but many find them difficult to grow in a North Carolina garden. They are susceptible to a multitude of soilborn, wind dispersed, and insect transmitted diseases including Bacterial Canker, Bacterial Spot, Bacterial Wilt, Botrytis Gray Mold, Collar Rot, Damping Off, Early Blight, Foliar Fungal Diseases, Fusarium Wilt, Gray Leaf Spot, Late Blight, Pith Necrosis, Septoria Leaf Spot, Southern Bacterial Wilt, Southern Blight, Tobacco Mosaic Viruses, Tomato Spotted Wilt Virus, Tomato Yellow Leaf Curl Virus, and Verticillium Wilt. There are also a variety of insect pests and Root Knot Nematodes are another pest. In addition, calcium deficiency or improper watering can lead to Blossom End Rot.

Figure 1. Ripening Cherry Tomatoes.

Badly Drawn Dad  CC BY 2.0

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Figure 1. Ripening Cherry Tomatoes.

Badly Drawn Dad  CC BY 2.0

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There are more than 10,000 tomato varieties. Choose which ones to grow based on: disease resistance, likelihood of thriving in your garden conditions (available space, climate zone, sunlight, type of soil), fruit size, flavor, nutritional value, color, intended use (fresh vs. canning), whether you want to save seeds, and whether you want a vine or a bush. Review recommendations from gardeners near you in the online database - Vegetable Varieties for Gardeners,

Disease Resistance

When possible, select plants with known resistance to common diseases. Look for the following letters on the plant tag/seed packet which indicate resistance to specific diseases.

• EB- Early blight

• F - Fusarium Wilt

• LB- Late blight

• N - Nematodes

• ToMV - Tobacco Mosaic Viruses

• TSWV - Tomato Spotted Wilt Virus

• V - Verticillium Wilt

Hybrid vs. Open Pollinated and Heirloom Seeds

Hybrids are the result of controlled breeding of two different parent plants to produce offspring with a combination of specific traits such as disease resistance, fruit quality, yield potential, and other horticultural traits. However, the offspring of hybrid plants won’t necessarily carry those desirable traits into the next generation, so seed saving is not advisable.

Open-pollinated varieties have traits that reliably carry through to the next generation, and seeds can be saved to grow similar plants again later. Tomatoes are self-pollinated, so even if several varieties of open-pollinated tomatoes are grown near each other, the seeds can still be saved and are likely to breed true to the parent plant.

Heirlooms are open-pollinated varieties that have been cultivated and passed down through generations.

Bear Fruit All at Once or Throughout the Season

• Determinate varieties are compact, bush tomatoes that do well in tomato cages. They grow to full size, then flower and fruit, producing a fruit cluster on stems between each leaf, and each stem terminates in a fruit cluster. The main harvest occurs over a few weeks, and then the plants die; they will not produce tomatoes throughout the summer. These are a great choice for canners who want to harvest lots of tomatoes at once, or folks who travel during the late summer. Most early-ripening tomato cultivars are determinate. Some varieties in this group are Colonial, Mountain Crown, Mountain Delight, Mountain Fresh, Mountain Pride, Mountain Regina, Mountain Ruby, Pik Red, Sunny, Sunrise, and Roma.

• Semi-determinate varieties are compact bushy plants that set fruit and ripen over a longer period of time than determinate varieties. Celebrity is an All-America Selection award-winning semi-determinate tomato.

• Indeterminate varieties are vines that continue to grow, flower, and fruit throughout their life. They can reach 10 to 12 feet tall and should be grown on a trellis or fence. They produce a fruit cluster on the stems between every third leaf, with tomatoes ripening throughout the season. Most of our home garden varieties in North Carolina belong to this group, including Manapal, Better Boy, Big Boy, Fantastic, and Cherokee Purple. Most heirloom varieties are indeterminate.

Time Until Fruiting

• Early-season tomatoes ripen in 50 to 65 days after transplanting and include Celebrity, Bush Early Girl, Early Girl, Juliet, and Super Sweet 100.
• Mid-season tomatoes ripen in 66 to 80 days after transplanting and include Better Boy, Big Beef, Big Boy, Brandywine, and Cherokee Purple.
• Late-season tomatoes require more than 80 days to ripen and include varieties such as Beefsteak and German Pink.

Use Fresh or Preserve by Drying or Canning

• Slicing – large and juicy tomatoes are best for eating fresh. Celebrity, German Johnson, and Better Boy are several examples.

• Paste – fleshy tomatoes good for cooking, canning and drying. Collectively known as Roma Tomatoes, popular varieties include Heinz Super Roma, Mountain Crown, Plum Regal and San Marzano.

• Cherry – small, juicy and flavorful, great for grazing in the garden and an easy addition to salads. These are the easiest to grow! Black Cherry, Sungolds and Super Sweet 100 are common varieties.

Grafted Onto Disease-Resistant Rootstock

Grafting a tomato variety with desirable fruit characteristics onto the rootstock of a variety that is resistant to soil-borne diseases, has a higher stress tolerance, or a more vigorous root system may increase the likelihood of success. Grafting a variety that is resistant to wind- and insect-vectored diseases onto the rootstock of a variety resistant to soilborne diseases results in a plant more resilient than either of the individual varieties.

Strategies for Success

Choose varieties that consistently perform well. e g. Better Boy, Celebrity, and Improved Whopper are VFN, which means they carry resistance to verticillium wilt, fusarium wilt, and root-knot nematodes. Experiment with several varieties to find the ideal tomato for your taste buds and garden.

If growing from seed, obtain seeds from a reputable source, and sow seeds in individual pots six to ten weeks before the last frost. Do not touch or handle seedlings. Without touching the plant, discard the entire pot, soil, and seedlings that show leaf twisting, mosaic, or unusual growth. Wash hands before working with any other seedlings.

Submit a sample of your garden soil for testing, and amend it according to the recommendations in the test results. Place 2 to 3 inches of compost on top of the planting area, then use a garden fork to turn it into the top 6 to 9 inches of soil.

Tomato plants should be spaced 1 ½ to 2 feet apart in the row with 3 to 4 feet between rows. When handling seedlings, lift them by the roots or the leaves; do not hold them by the stem, as it is easily damaged. For ungrafted plants, the planting hole should be deep enough to cover the top of a peat pot with one inch of soil. If the peat pot is exposed to air, it will act like a wick, rapidly drying out the root ball and causing stunting or death of the plant. If the transplant is tall and leggy, dig a horizontal trench rather than a hole for each plant. Remove all but the top 4-5 leaves and lay the plant on its side in the trench. Cover the root system and bare stem up to the top leaf cluster with 2 to 3 inches of soil (ensuring the peat pot is buried at least 1 inch below the soil surface). Firm the soil over the plant and water well.

If transplanting grafted tomatoes, plant in the ground at the same level they were growing in the pot. The graft must remain at least 1 inch above the ground to prevent the portion above the graft from developing roots in the soil, which would defeat the purpose of the graft.

Tomato plants should be staked or caged shortly after planting. Generally, staking produces larger tomatoes but fewer than caging. A common 6-foot tomato stake may be purchased from many garden centers. The stake should be driven in the soil about one foot deep, 3 to 5 inches from the plant. Be sure to avoid driving the stake into the root side of plants that have been trench-planted. Trench-planted tomatoes should be staked immediately after planting while the location of the buried stem is fresh in mind. Use a strip of cloth, nylon stocking, or heavy string to tie the plant to the stake.

Tomato cages may be made using a 5½-foot length of concrete reinforcing wire or pasture wire. The wire will form a circle 18 to 20 inches in diameter. The bottom horizontal ring of the wire cage should be cut off so that the ends can be pushed into the ground. After setting the cage in place over the tomato plant, drive 2 or 3 stakes around the outside edge of the cage to give it extra support.

Sidedress tomato plants with 2 to 3 tablespoons per plant of a complete fertilizer such as 8-8-8 or 10-10-10 after the plants have started to set fruit and 4 to 6 weeks thereafter throughout the growing season. Keep the sidedressing material 4 to 6 inches from the plant's stem to avoid fertilizer burn.

It is important to ensure the tomatoes receive sufficient water during the season. The soil should be soaked to a depth of 6 to 8 inches at 7-day intervals. Mulches such as wheat straw or composted leaves around tomato plants will conserve soil moisture and break down, adding organic matter to the soil.

Spend time in the garden and intervene early when you see signs of pests, diseases, and weeds. Eliminate weeds in and around the garden bed. Give beneficial insects a chance to manage thrips and aphids, but if the pest populations build up, intervene early in the season to reduce initial infection and spread. Contact your local horticultural extension agent for information on the use of insecticides and herbicides. When working with tomatoes, regularly clean tools and disinfect by spraying with 70% isopropyl alcohol. Soaking tools for 10 minutes in a 10% household bleach solution, then rinsing with water, is another option. Remove and destroy symptomatic plants whenever they appear. Remove and destroy all tomato plants at the end of the growing season. Plant tomatoes in a different place each year to avoid building up pests and diseases in the soil.

Figure 2. Both determinate and semi-indeterminate tomatoes do well in containers at least a foot deep with drainage holes.

Scott Rubin, Flickr  CC BY 2.0

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Figure 2. Both determinate and semi-indeterminate tomatoes do well in containers at least a foot deep with drainage holes.

Scott Rubin, Flickr  CC BY 2.0

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Figure 3. Tomato plants grown in cages

Bobistraveling, Flickr  CC BY 2.0

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Figure 3. Tomato plants grown in cages

Bobistraveling, Flickr  CC BY 2.0

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Blossom-end rot of tomatoes is a physiological disorder caused by a lack of sufficient calcium in the blossom end of the fruit (Figure 4). This disorder causes decay of tomato fruits at the blossom end, with dry, brown areas that grow to the size of a half-dollar. This disorder is usually most severe following extremes in soil moisture (either too dry or too wet). In some cases, the soil does contain sufficient calcium, but irrigation is low and does not allow the correct adsorption of the nutrient.

To Reduce Blossom-End Rot in Tomatoes

1. Follow the directions provided with the results of the soil test to bring the pH to 6.5 - 6.7

2. Mulch plants with compost, woodchips, or other organic matter to conserve moisture.

3. Irrigate when necessary - Tomato plants require about 1.5 inches of water per week during fruiting. This amount of water should be supplied by rain or irrigation. Extreme fluctuations in soil moisture lead to a higher incidence of blossom-end rot.

Figure 4. Blossom End Rot (BER) in tomatoes at Clinton, North Carolina.

Courtesy of Dr. Emmanuel Torres.

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Figure 4. Blossom End Rot (BER) in tomatoes at Clinton, North Carolina.

Courtesy of Dr. Emmanuel Torres.

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Indeterminate types produce a shoot or "sucker" at each leaf axil. These suckers, if left undisturbed, grow into larger stems and produce fruit. This type of plant is usually supported above ground with a stake or trellis. A 5- to 7-foot stake may be driven into the ground, and the stems tied loosely to it with soft twine or cloth. Trellised tomatoes may be handled in a similar manner, leaving one stem for each 8 to 12 inches of space in the row; that is, if plants are spaced 3 feet apart, leave 3 stems per plant; if plants are spaced 2 feet apart, leave 2 stems per plant. Break out all other suckers before they grow to 3 inches long.

Determinate types are usually pruned only once when suckers are 2 to 4 inches long (later pruning reduces size). The plants are normally spaced 1 to 2 feet apart in the row. The plant is sometimes tied to a stake. More often, plants are supported in a weave of strings supported by stakes. Place 1” X 2” stakes between every other plant, and 2 additional stakes side by side at each end of a section. These sections are usually no more than 50 feet long. This break provides a path to carry fruit out of the garden. When plants are about 12 inches tall, the first string is tied to the stalks at one end of a section. Then, pulling the string as tight as possible, wrap it around each stake, keeping it tight (this takes practice). The string is stretched down one side of the row and then back up the other. When one returns to the starting point, the string is tied again. A second string is added in a week or two, when the tops of plants are 8 to 10 inches above the first string and before plants begin to flop over. Usually, only 4 strings are needed to support a crop. Many people use a 12- to 36-inch stick with a hole at the end to guide the string around the stake. With a little practice, stringing can be done at a slow walk. Nylon "baler's" string usually is used because it does not stretch like "binder's twine."

Wire supports can be used like string, but the larger posts are spaced 10 to 15 feet apart. Wire is stretched on both sides of the row every 7 to 14 days as the plants grow. This wire is attached to fence posts with a nail or fence staple at the end of each row. Plants are not normally pruned in this system.

Wire cages are often used to support tomato plants in home gardens. A cylinder, about 2 feet in diameter and 3 to 5 feet high, is made from strong hog wire used for reinforcing concrete. This cylinder is placed over the plant and anchored to the ground. Plants growing in cylinders are normally spaced 3 to 4 feet apart in the row and are not pruned; rather, the suckers are pushed back in the cage to force them to grow upward. This is a good system to use if only a small number of plants can be grown, since yield per plant is generally higher than with other training systems.

• Tomato profile in the Extension Gardener Plant Toolbox.

• Vegetable gardening chapter in the SE Extension Gardener Handbook.

• Viral Disease of Tomatoes

Printable Tomato Disease Picture Guides

• Common Diseases of Tomatoes in NC (size: 42" x 36" PowerPoint)

• Common Foliar Tomato Diseases in North Carolina (size: 8.5 x 11 PDF)

• Common Soilborne Tomato Diseases in North Carolina (size: 8.5 x 11 PDF)

Disease Diagnostic Videos

• Bacterial spot of tomato

• Bacterial wilt of tomato

• Gray leaf spot of tomato

• Late blight of tomato

• Early blight of tomato

• Septoria leaf spot

• Southern blight of tomato

• Verticillium wilt of tomato

The author wishes to thank Larry Bass and Douglas Sanders for their work on previous editions of this publication and Dilip Panthee and Emmanuel Torres-Quesada for reviewing and improving this edition.