Waiting for harvest can be one of the more tedious parts of gardening. Instant satisfaction can be had when you're perusing a farmer's market or grocery store, but not when you're growing things yourself--those juicy tomatoes you crave may well take months to get into your sandwich. But there are many vegetables, warm- and cool-season, that take less time to grow than others, making them particularly suitable for children, and for mixing with longer-germinating crops.
According to the University of Tennessee Extension, many onion varieties can take as little as 30 days or up to 60 to mature enough to harvest. They can be planted very early, in February or March, or as a fall crop. The Texas A&M University Horticulture Department explains differing onion types form bulbs at different rates, depending on the length of the days, and all require more water the closer they get to harvest.
Turnips grown for their greens, rather than roots, can be planted in March and take between 30 and 40 days to mature. Heirloom Organics says optimal growth is dependent upon a site with deep, loose and fertile soil.
Summer squash, once seeds sprout and plants become established, grows prolifically if given enough water and sun. The fruit is ready to be harvested from the sprawling plants between 40 and 50 days after planting in early summer. The University of Illinois Extension advises picking fruit before it matures and the rind hardens, about four to eight days after flowering.
Cucumber can be harvested around the same time as summer squash. Vegetables being grown for picking or slicing can be picked as soon as 50 days later, before they reach the yellowing stage, the Ohio State University Extension states.
Healthy snap bean plants in bush varieties produce a large crop within about 50 days, after they bloom. They work well planted successively from April through June and grow best when there is a constant moisture supply, Fort Valley State University claims.
Radishes, often grown as an early spring or fall crop, are one of the quickest growing vegetables. They will reach maturation as soon as 35 days and serve as a good "intercrop" among longer-maturing vegetable plants, says Heirloom Organics.
Another fall vegetable, leaf lettuce can be harvested within 40 to 50 days after planting in July, August and September. It is cold hardy, but hot weather can stunt growth and make leaves taste bitter, according to the University of Illinois Extension.