Vegetable gardening is an exercise in patience. Sweet potatoes can take more than 100 days to ripen; some tomato and watermelon varieties require five months.But there are ways to shorten the wait.The easiest is choosing plants that taste best when harvested young."The one thing you will miss out on with speedy growing is bulk, but what you will get in return is layers of flavor; a sprinkle of hot and peppery micro-green radish here, a sweet and nutty, barely cooked new potato there, a garnish of cucumber-y borage flowers to finish a dish," writes Mark Diacono in the new The Speedy Vegetable Garden (Timber Press, $18.95). "These are the crops that will mark out your cooking as distinctly and unquestionably homegrown."Timing is everything."Be slow to harvest and you'll miss their best moments," says Diacono, who does his gardening on a 17-acre plot in Devon, England. "These are fresh, lively and zingy flavors, flavors that can either fade or become bitter and overly strong as the plant grows on toward maturity."Many plants -- notably fruits -- are genetically wired for late development."Tomatoes, strawberries and apples all want to be left on the plant until they are fully ripe to get the fullest, lushest flavors out of them," Diacono says. "Vegetables are a little different. Many get woodier, less succulent and lower in sweetness as they grow more mature, so really are at their loveliest picked young."That includes new potatoes, radishes, baby carrots, zucchini, miniature cucumbers, spring peas, turnips and beets.Cut-and-come-again salad leaves can be clipped in as little as 21 days.Sprouted seeds (mung beans, mustard, lentils) can become table fare in just three days.Check the maturity dates on seed packets as you shop. Heirloom tomatoes take 100 days or more to develop, while cherry tomatoes need only about 65 days.The same goes for squash. Winter squash (acorn, butternut) generally require 110 days before they are kitchen-ready. Summer squash (crookneck, zucchini), by comparison, can be eaten in 55 days or less.There are many ways to jumpstart the growing season so you can be harvesting a meal while other gardeners are just beginning to turn the ground. Among them:Choose the warmest site possible if you're planting early.Use enclosures. Covering plants moderates temperature, wind and humidity.Start vegetable plants inside from seed, and transplant them eventually into the garden.Warm the soil early.