Knowing when to harvest your vegetables is as important as knowing how to grow them. Each different vegetable has an optimum time for harvest. While some vegetables are forgiving if left a bit long in the garden, others can go from tender and tasty to tough and bitter overnight. This is particularly true if you are planning to can or freeze them. An over mature green bean certainly will not be improved by preservation. You cannot always rely on the Adays to harvest@ on seed packets, as growth and maturity depends on many environmental factors such as precipitation, temperature, and soil fertility. As any gardener knows, these can vary greatly from year to year. The best way to determine when a vegetable is ready to harvest is from the characteristics of the plant itself, and sometimes by sampling the veggies right in the field.
Asparagus: Asparagus can be harvested the third year after planting crowns, but do not harvest for more than one month the first year. In the following years, harvest the spears in May and June. Harvest spears 5 to 8" tall by cutting 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; store in the refrigerator without washing.
Snap Beans: Snap beans are best when the pods are firm and snap readily, but before the seeds within the pod develop. The tips should be pliable. Bean pods will be the most tender when the small seed inside is one-fourth normal size. From this stage on, the pods become more fibrous and the beans more starchy. Keep cold (45 to 50° F.) and humid and use as soon as possible. Washing before storage helps retain moisture content.
Shell Beans: Let them dry on the vine, then shell and store cool and dry for winter use.
Beets: Harvest beets when they are 1 1/4 to 2" in diameter. The beet tops can also be eaten as greens. The leaves should be 4 to 6" long. Wash and refrigerate immediately. Harvest fall beets before the first moderate freeze or mulch heavily for winter harvest.
Broccoli: Cut broccoli when the buds are compact but before they turn yellow or open into flowers. Leave 5 to 6" of stem attached. Side shoots that develop in the axils of the leaves can be harvested as they enlarge.
Brussels Sprouts: The small sprouts may be picked or cut when they are firm and about 1" in diameter. Pick the lower sprouts as soon as they are large enough for use. Remove lowest leaves from the stalk to improve sprout size. Frost improves flavor, but harvest before first severe freeze.
Cabbage: Cut the heads when they are solid, but before they crack or split. In addition to harvesting the mature head, 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@ in diameter and should be picked when they are firm. Excessive water uptake by plant roots causes splitting. To prevent mature heads from splitting, twist plants enough to break several roots. Store cabbage in crisper and use within 1 to 2 weeks.
Carrots: Harvest at 1 to 2" thickness. Always pull the largest carrots in the row first. Remove tops and wash before transferring to refrigerated storage. Fall planted carrots should be harvested before the ground freezes, or mulched heavily for winter harvest.
Cauliflower: Tie outer leaves above the head when curds are about 1 to 2" in diameter. Heads will be ready for harvest in 1 to 2 weeks. Curds exposed to sunlight become creamcolored, rough in appearance and coarse textured. Chill soon after harvest.
Chard, Swiss: A green that may be harvested continuously by breaking off outer leaves. Spring planting will provide greens from early summer to first moderate freeze.
Cucumber: Harvest when fruits are bright, firm and green before they get too large. Cucumbers are best when slightly immature, just as the spines soften and before the seeds become half-size. This will vary with variety. Most varieties will be 1.5" to 2.5" in diameter, 5 to 8" long. Pickling cucumbers will be blocky and not as long. Store in the refrigerator.
Eggplant: Harvest when fruits are near full size (approximately 6 to 8" in diameter) but still firm and bright in color. Older fruits become dull colored, soft and seedy. Keep cool and humid.
Garlic: Harvest when the lower leaves turn brown. Remove flower stalks as they form to improve the size of the heads. Allow heads to dry completely in a shaded, dry area; remove stalks when dry. Store in cool, dry place.
Lettuce, Head: Harvest entire plant when head feels firm but before center bolts.
Lettuce, Leaf: Harvest outer leaves as they attain suitable size. Timely picking increases length of harvest.
Onions, Dry: Harvest at 1/4" to 1" for fresh table use, 1 to 1.5" for boiling and pickling, and when tops have fallen over and necks are shriveled for storage and general cooking. Pressing with fingers will not dent mature bulbs. Cure onions by placing in a single layer or mesh bag in a dry, well-ventilated area out of direct sunlight for 3 to 4 weeks. Remove tops when fully dry.
Peas: If you expect to shell the peas, harvest pods when they are shiny green and fully developed. Overly mature peas are poor quality. For edible-podded varieties (snow, Chinese) harvest when pods are fully developed (about 3") before seeds are more than one half developed. Deterioration proceeds rapidly at high temperatures. Wash and chill immediately.
Peppers, Hot: Harvest as needed. Young, green peppers are hotter than mature, colored ones. For long-term storage, pull plants late in season and hang to dry in a warm, wellventilated place.
Peppers, Sweet: Harvest when fruits are firm and full size. If red fruits are desired, leave on plant until red color develops.
Potatoes: "New" potatoes can be dug before the vines die. For large potatoes, wait until the vines die and the ground is dry. Use a spading fork and dig 4 to 6" beneath the soil surface. Handle the tubers gently during harvest to avoid bruising. Cure for 10 to 14 days in a dark, wellventilated location at 45° to 60° F.
Summer Squash: Best when harvested young and tender; skin should be easily penetrated with the thumbnail.
Winter Squash: Maturity can be roughly determined by pressure from the thumbnail on the fruit skin. Mature fruit will be hard and impervious to scratching. Harvest squash before the first hard frost, leaving at least 1" of stem attached. Fruit picked without the 3 stem will soon decay around the stem scar. Cure in a dry, well-ventilated area for 10 days at 75 to 85° F.
Sweet Potato: Harvest in fall before frosts and freezing temperatures. Handle carefully when digging as bruised tubers will rot. Cure for 1 week at 80 to 85° F.
Tomato: Harvest when fruits are uniformly red, but before end softens. Vine-ripened tomatoes are sweetest, but tomatoes will ripen off the vine if picked green. Green tomatoes, harvested before frost, should be wrapped in newspaper and kept at 55 to 70° F. Tomatoes stored in this manner should last 3 to 5 weeks. Be sure to inspect each week for ripeness.