Gardening takes time, and many vegetables require months of care before harvest. For the impatient gardener, choosing the fastest growing vegetables will provide gratification sooner than those with a long growth season. Generally, the smaller the vegetable, the less time it requires for growth.
According to the University of Illinois, most varieties of radishes mature in 20 to 30 days. Plant radishes during cool weather. For spring planting, look for: Burpee White, Champion, Easter Egg, Cherry Belle, Early Scarlet Globe, Fuego, Purple Plum and Snow Belle varieties which all take between 22 and 28 days from seed to harvest. Summer radish varieties such as French Breakfast and Icicle take 23 and 25 days, respectively to mature. Winter radish types (China Rose, Chinese White, Round Spanish Black and Tama hybrid) take twice as long to mature, but they grow larger in size.
According to the Houston Chronicle, most lettuce varieties mature in 30 to 60 days. The actual growth time depends on the variety of lettuce you plant and the size to which you allow it to grow. Opt for looseleaf varieties for the fastest growing lettuces. The University of Wisconsin recommends harvesting lettuce when the leaves measure 4 to 5 inches.
Bunch (Spring) Onions
Between 30 and 60 days after planting, small bunch onions will be ready for harvest. The University of Tennessee recommends harvesting these when the bulbs measure between 1/2 and 1 inch in diameter.