Asparagus can be harvested the third year after planting crowns, but do not harvest for more than one month the first time. In the following years, the spears may be harvested in May and June. Harvest spears 5 to 8 inches tall by cutting them or snapping them off. Cutting may damage some spear tips that have not yet emerged from the ground. To snap a spear, bend it from the top toward the ground. Asparagus deteriorates rapidly after harvest. If it is not eaten immediately, it should be processed or refrigerated.
Beans and Peas
Snap beans are best when the pods are firm and snap readily, and are thinner than a pencil. The tips should be pliable. Green beans planted in mid- to late spring continue to set beans through most of the summer if you keep picking the ripe beans.
Pick Lima beans (and other beans where the inner bean is the harvest) when the pods are well-filled but before they turn yellow. The end of the pod should feel spongy.
Harvest peas when the pod is full and green and the peas are still tender and sweet. Test for maturity frequently by picking a couple of pods and examining them for firmness. Harvest snow peas when the pods are 1 1/2 to 2 inches long and the peas are about the size of BB's. The pods are usually picked 5 to 7 days after flowering.
Harvest beets when they are 1 1/4 to 2 inches in diameter. The beet tops can also be eaten as greens. The leaves should be 4 to 6 inches long.
Cut broccoli when the buds are compact but before they turn yellow or open into flowers. Leave 5 to 6 inches of stem attached. Side shoots that develop in the axils of the leaves can also be used.
The small sprouts may be picked or cut when they are firm and about 1 inch in diameter. Pick the lower sprouts as soon as they are large enough for use. Lower leaves may be removed to allow more room for sprouts to develop.
Cabbage and Kale
For regular cabbage, cut the heads when they are solid, but before they crack or split. In addition to harvesting the mature heads, you can harvest a later crop of small heads or sprouts that develop on the stumps of the cut stems. The sprouts will be 2 to 4 inches in diameter and should be picked when they are firm.
Cut the Chinese Cabbage entire plant at the ground line when the heads are compact and firm. Harvest before the seedstalks form in the early summer, and before freezing temperatures in the fall.
Carrots are ready for use when they are young, crisp, and 1/2 to 1 inch in diameter. The sugar content is higher in mature carrots, but the younger ones are more tender. Carrots planted in the summer may be left in the ground until a killing frost. A straw mulch can be placed over the row so that the carrots can be harvested until the ground freezes solid.
Harvest before the heads become overmature and "ricey." The heads should be compact, firm, and white. To keep the head white, tie the outer leaves together over the center of the plant when the head begins to form. Cauliflower will grow 6 to 8 inches in diameter and is ready for harvest 7 to 12 days after blanching.
Pick corn when the silk turns dark and starts to shrivel. The kernels should be bright, plump, and milky. This stage occurs about 20 days after the appearance of the first silk strands. To harvest, snap off the ears by hand with a quick, firm, downward push; then twist and pull. Corn is at its prime eating quality for only 72 hours before becoming overmature.
Cucumbers may be picked when they are 2 inches long or less for pickles, 4 to 6 inches for dills, and 6 to 8 inches for slicing varieties. A cucumber is at its highest quality when it is uniformly dark green, firm, and crisp. Cucumbers are past their prime if they are large, dull, puffy, and yellow. Remove old fruits from the vine so that young fruits will develop.
Harvest eggplant when the fruits are 6 to 8 inches long, glossy, and have a uniformly deep color. The fruits are overmature when they become dull, soft, and seedy. Use a knife or pruning shears to cut the fruit off the plant. Leave the green calyx attached to the fruit.
Pull up the bulbs when the tops start to yellow and dry. Place the bulbs on screens to dry. When dry, trim the roots out close to the bulb, remove the loose outer sheaths, and store under cool, dry conditions.
Dig the roots anytime from late fall after a hard freeze until growth starts in the spring.
Dig the tubers anytime from September until after a frost, and in the spring before the new growth starts.
Break off the outer leaves as they become 8 to 10 inches long. New leaves will continue to grow from the center of each plant.
The best time to harvest is when the bulbous part is 2 to 3 inches in diameter (size of a golf ball). Large, older kohlrabi is tough and woody and may have an off flavor. The young leaves can be cooked like spinach.
Leaf lettuce and other greens can be grown as cut-and-come-again vegetables. As they get 4 to 6 inches tall, cut the tops, leaving the crowns intact so they will regrow. Butterhead varieties form small, loose heads that are ready in 60 to 70 days. May be picked when plants have 6 to 8 leaves until the seed stalk develops. Cut while young, taking the entire plant off at the soil surface.
Harvest Chard when they become 8 to 10 inches long while they are still young and tender. New leaves will continue to grow from the center of the plant.
For Endive/escarole Cut the plants at the ground level when they are fully developed (10 to 12 inches across) and the center leaves have been blanched.
Harvest in late summer and fall by loosening the soil with a spading fork and pulling out the plant. Cut off the roots and all but 2 inches of the green leaves.
Cantaloupes and muskmelons develop their best flavor when they ripen in warm, dry weather. As the melon ripens, the stem separates readily from the fruit. After harvesting, the fruit can be held at room temperature for 1 to 3 days until the blossom end softens.
Use a combination of the following indicators to determine when watermelons are ripe; (1) light-green, and when the curled tendril near the stem begins to shrivel and dry up; (2) the surface color of the fruit turns dull; (3) the skin is rough and resists penetration by a thumbnail; and (4) the bottom of a melon where it touches the ground turns from a light green to a yellowish color. Watermelons will not continue to ripen after harvest.
The okra pods should be harvested while they are immature and still tender (2 to 3 inches long). The large pods become tough and woody. The pods must be picked at least every other day if you want the plants to remain productive.
Green onions may be harvested when the tops are 6 inches high and the stem is the thickness of a pencil. Harvest dry onions in late July or early August after most of the tops have fallen down. Allow the bulbs to air dry for a day or two after digging. Then they can be stored in a dry shelter on slats or screens, or hung in small bunches. Complete drying or curing takes 2 to 3 weeks. After curing, the tops should be cut 1 1/2 to 2 inches long. Place the bulbs in dry storage with good air circulation.
Parsnips should be left in the ground until the tops freeze, since they are not fully flavored until after early frosts. The moderate sizes are best. Larger ones may be woody. If you do not have storage facilities, you can leave the roots in the ground and mulch them with straw so they can be dug up throughout the winter.
Harvest in early to mid-October, before a hard freeze. The plants turn yellow when they are mature. Dig up the entire plant and shake the soil off the peanuts. Cure them by stacking the plants in an open shelter or by hanging them in a warm, dry shed or garage for a week. After the plants have dried, shake off any remaining soil and pull the peanuts from the vine. Continue to air dry for another week or two. When the peanuts are dry, they are ready to shell or roast.
Sweet Peppers may be harvested at any size, but they are usually picked when they are full grown and mature. They may be left on the plant to ripen fully to a red or yellow color, in which case they will be mellower and sweeter.
Hot peppers, except Jalapeno (which remains green when ripe), are usually harvested at the red ripe stage. Other hot peppers should be left to ripen to their full color on the plant. Wear gloves when handling them and avoid touching your face—the oils are very pungent.
"New" potatoes can be dug before the vines die. Fingerling (or new) potatoes are ready for digging when the plants finish blooming.
For large potatoes, wait until the vines die. Use a spading fork.
Dig 4 to 6 inches beneath the soil surface. Handle the tubers gently during harvest to avoid bruising. Dig the potatoes, spread them on the soil to dry, then brush off the soil and store them in an airy, cool, dark place.
For the best flavor, start thinning and eating radishes when they are the size of marbles. They will be good up to 1 inch in diameter. After that, they may become hot and pithy.
Do not harvest the first year. Harvest only for 1 to 2 weeks the second year. Thereafter, stalks may be harvested for 8 to 10 weeks. To harvest, pull the leafstalks from the plant. Only the stem (petiole) is used, since the leaves contain large amounts of oxalic acid and should not be eaten.
Summer squash should be harvested while still young and tender - 6 to 8 inches in length and 1 1/2 to 2 inches in diameter. Scallop squash are best while small, 3 to 4 inches in diameter and a grayish or greenish white in color. Squash grown rapidly and are usually ready to pick 4 to 8 days after flowering.
Harvest winter squash and Pumpkins when the vines have died back and the fruit is has a fully-colored and hard rind, but before a heavy frost. Cut squash from the vines carefully, leaving 2 inches of stem attached. Avoid cuts and bruises. Store in a dry location at 50 to 55 degrees.
Harvest in the fall before frost kills the vine. Handle carefully when digging to avoid bruises. After digging, let the roots lie exposed for 2 or 3 hours to dry thoroughly, then put them in a warm room to cure for about 10 days. Store at 50 to 55 degrees F and 85 percent humidity.
During hot summer weather, pick the tomatoes when they have a healthy pink color and let them ripen indoors. Tomatoes do not need to be in the sun in order to ripen. If you have green fruit on the plants in the fall when frost is approaching, pick the tomatoes and store them in a cool, dark place to ripen.
Tomato stems are tough, so harvest the tomatoes with garden scissors or pruners rather than just yanking them off the vine. For best flavor, pick ripe tomatoes just before you're going to eat them. If you're picking a few days' worth of tomatoes, store them out of direct light at room temperature. Green (unripe) tomatoes will ripen on the kitchen counter.
Harvest when the roots are 2 to 3 inches in diameter. The tops can be used for greens when they are 4 to 6 inches long. Turnips can be left in the ground after a heavy freeze and mulched with straw for harvest during the early winter.