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For optimum quality, harvest vegetables at the right time

It’s that time of year when most gardeners are chomping at the bit to taste that first juicy, ripe tomato or first ear of corn. In order to harvest vegetables at their peak of tenderness and sweetness, it’s important to be able to tell when that time is. Many vegetables, because the process of ripening continues even after they are picked, should either be used immediately or stored in the refrigerator to slow down this process. This is especially true of tomatoes, sweet corn, snap beans, summer squash, beets and cucumbers. The sugars of some vegetables like corn and peas change to starch very rapidly unless refrigerated immediately.

Vegetables should be picked at the proper time not only to assure the best quality, but also to arrive at their optimum vitamin and mineral content. Harvesting at the proper stage will also tend to keep the plants producing. The following suggestions are offered as guidelines to help you harvest your vegetables for optimum quality.

Sweet corn should be picked when the silk turns dark and begins to shrivel; Kernels should be bright, plump and milky. If small and soft, they are tasteless; if large and hard, they are starchy and flavorless. Keep ears cool and cook within an hour if possible. As the ear develops, the husks tighten, becoming firm and solid when they are ready for harvest——much like a glove fits the hand.

Potatoes can be harvested any time the tubers are big enough to use. If you intend to store them for some time, it is best to let the plants reach maturity. After the vines have completely died, wait two weeks before beginning to dig them. This will allow the skins to thicken and the tubers to fully mature. Dig them carefully, preferably with a spading fork. Don’t bruise or cut them, and don’t expose them to the sun for any length of time. Store them in a cool, absolutely dark place where they will not freeze. Temperatures of 35 to 40° F are best.

Onions should be picked when they are ¼ to ½ inch in diameter for fresh table use, when 1 to 1 ½ inches for boiling or pickling, and when tops have died down for storage and other uses. Onions grow best during the cool, moist weather of spring and early summer. The warm, dry conditions of midsummer are needed as the crop matures. This will produce a sweet, firm onion with good keeping quality. The best time to harvest onions is when the tops turn yellow and break over just above the bulb.

Winter squash, such as Table Queen, Hubbard, and Turbans, develop a hard shell. As the squash ripens, it develops a glossy, somewhat sparkling color, with some yellow in the ground color. As winter squash become mature, the rind hardens so that it is not readily penetrated by a thumbnail. Leave two inches of stem on the squash. Place the squash in a moist sheltered place at 80 to 85° F for two weeks to harden off. Squash will keep best when stored at 55 degrees in a dry area such as an attic.

Summer squash should be harvested when they are very young and tender. The early varieties such as Zucchini, Crookneck and Patty Pan, reach the edible stage within a few days after full bloom.

For best quality and flavor, tomatoes should be allowed to ripen on the plants. Green tomatoes can be picked and stored in a cool, moist, dark place. To ripen them, simply bring them into a warm room. Light is not essential for ripening. In the fall, entire plants along with their green fruit can be lifted and stored in a cool, frost-free area such as a garage or basement. Fruit can be ripened by exposing them to warmer temperatures. Refrigerating ripe tomatoes reduces the flavor and changes the fruit texture.

In order to get pure white heads on cauliflower, the outer leaves need to be tied together as soon as the head has reached a diameter of 2-3 inches. Examine the heads every few days to determine when to tie and when to harvest. Harvest the heads when they are still compact and fairly smooth. The bud segments should not be allowed to separate.

Cabbage heads are usable as soon as they become fully firm. Heads will split if they become over mature. Cutting just under the head to leave some basal leaves may cause small lateral heads to develop as a bonus.

This column is printed as a service of the Washington State University Extension Office at Elma. Donald D. Tapio is the regional gardening and farming specialist for Grays Harbor and Pacific counties. He can be reached at (360) 482-2934 or

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