The nutritional content, freshness, and flavor that vegetables possess depend upon the stage of maturity and the time of day at which they are harvested. Overly mature vegetables will be stringy and coarse. When possible, harvest vegetables during the cool part of the morning, and process or store them as soon as possible. If for some reason processing must be delayed, cool the vegetables in ice water or crushed ice, and store them in the refrigerator to preserve flavor and quality. The following guidelines can be used for harvesting vegetable crops.
Asparagus - Harvest the spears when they are at least 6 to 8 inches tall by snapping or cutting them at ground level. Up to 8 spears per plant may be harvested the second year after planting. A full harvest season will last 4 to 6 weeks during the third growing season.
Beans, snap - Start harvesting before seeds develop in the pod (about the diameter of a pencil). Beans are ready to pick if they snap easily when bent in half.
Beans, lima - Harvest when the pods first start to bulge with the enlarged seeds. Pods must still be green, not yellowish.
Broccoli - 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 will develop later, providing a continuous harvest.
Brussels sprouts - Harvest the lower sprouts (small heads) when they are about 1 to 11⁄2 inches in diameter by twisting them off. Lower leaves along the stem may be removed to hasten maturity.
Cabbage - Harvest when the heads feel hard and solid.
Carrots - Harvest when the roots are 3⁄4 to 1 inch in diameter. The largest roots generally have the darkest tops. Fall carrots can be left in the ground all winter and harvested as needed, if mulched.
Cauliflower - Exclude sunlight (blanch) when the curds are 1 to 2 inches in diameter by loosely tying together the outer leaves above the curd (head) with a string or rubber band. 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.
Collards - Harvest older, lower leaves when they reach a length of 8 to 12 inches. New leaves will grow as long as the central growing point remains, providing a continuous harvest. Whole plants may be harvested and cooked, if desired.
Corn, sweet - 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. Harvest ranges from 18 to 21 days after the silk appears.
Cucumbers - Harvest when the fruits are deep green, before any yellow color 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 4 to 5 times per week to encourage continuous production. Mature cucumbers left on the vine will stop production of the entire plant.
Eggplant - Harvest when the fruits are 3 to 5 inches in diameter and their color is a glossy purplish black. (A white variety of eggplant is also available.) The fruit is past its prime when the color starts to dull or become bronzed. Because the stem is woody, cut 3⁄4 do not pull 3⁄4 the fruit from the plant. A short stem should remain on each fruit.
Kale - Twist off the outer, older leaves when they reach a length of 8 to 10 inches and are medium green in color. Heavy, dark green leaves are over mature and are likely to be tough and bitter. New leaves will grow, providing a continuous harvest.
Kohlrabi - Harvest when the thickened stems or bulb (the edible part) is 2 to 3 inches in diameter by cutting off the plant just below the bulb. Stems become woody if left too long before harvest.
Lettuce - Harvest the older, outer leaves from leaf lettuce when they are 4 to 6 inches long. Harvest heading types when the heads are moderately firm and before seed stalks form.
Muskmelons (cantaloupe) - Harvest when the stem slips easily from the fruit with a gentle tug. Another indicator of ripeness is when the netting on skin becomes rounded and the flesh between the netting turns from a green to a tan color.
Mustard - Harvest the leaves and leaf stems when they are 6 to 8 inches long. New leaves will provide a continuous harvest until they become strong in flavor and tough in texture from temperature extremes.
Okra - 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.
Onions - 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 the stem, leaving 2 to 3 inches attached, and store in a net-type bag in a cool, dry place.
Peas - Edible, podded cultivars should be harvested when pods are well rounded but before seeds are more than one-half of their full size. Harvest regular peas when the pods are well rounded, seeds are fully developed but still fresh and bright green. Pods are past their prime when they lose their brightness and turn light or yellowish green.
Peppers - Harvest sweet peppers when the fruits are firm, crisp, and full sized. Green peppers will turn red if left on the plant. Allow hot peppers to attain their bright red color and full flavor while attached to the plant; cut and hang them to dry.
Potatoes (Irish) - Harvest the tubers when the plants begin to yellow and die down. Store the tubers in a cool, high-humidity location with good ventilation, such as the basement or crawl space of the house. Avoid exposing the tubers to light. Greening, which denotes the presence of dangerous alkaloids, will occur even with small amounts of light.
Pumpkins - Harvest pumpkins and winter squash before frost and after the vines dry up, the fruit color darkens, and the skin surface resists puncture from your thumbnail. Avoid bruising or scratching the fruit while handling it. Leave a 3- to 4-inch portion of stem attached to the fruit and store in a cool, dry location with good ventilation.
Radishes - Harvest when the roots are 1⁄2 to 11⁄2 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 will become tough and woody.
Rutabagas - Harvest when the roots are about 3 inches in diameter. The roots may be left in the ground during winter and used as needed if properly mulched.
Spinach - 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.
Squash, summer - Harvest when the fruit is soft, tender, and 6 to 8 inches long (3 to 4 inches across for patty-pans types). The skin color often changes to a dark, glossy green or yellow, depending on variety. Pick every 2 to 3 days to encourage production.
Sweetpotatoes - Harvest the roots when they are large enough for use before frost. Avoid bruising or scratching during handling. (Damaged sweetpotatoes 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.
Swiss chard - Harvest by breaking off the developed outer leaves 1 inch above the soil. New leaves will grow, providing a continuous harvest.
Tomatoes - Harvest the fruits at the most appealing ripeness stage 3⁄4 up to fully red-ripe. (There are some yellow tomato cultivars.) Flavor is best at room temperature, but ripe fruit may be held in the refrigerator at 45°F to 50°F for 7 to 10 days.
Turnips - 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.
Watermelons - Ripe watermelons produce a dull thud rather than a sharp, metallic sound when thumped. Other ripeness indicators are a deep yellow 3⁄4 rather than white 3⁄4 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.
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Last modified: Jan. 15, 2015, 4:42 p.m.