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Timing matters when picking vegetables

When harvesting tomatoes, wait until they are “red” ripe.
When harvesting tomatoes, wait until they are “red” ripe. Centre Daily Times, file

Looking forward to harvesting warm season crops out of the garden, it is important to pick vegetables at their peak ripeness. For maximum quality and freshness it is important to harvest each vegetable at the proper time, which is its peak maturity or as soon as it is fully ripe. This is also the time of highest food value, vitamin content and taste.

It is best to pick vegetables in the early morning when they are still cool from the previous night and have the least stored “field” heat. Be careful to avoid bruising the vegetables when harvesting them — any wounds can result in a loss in quality, especially if you are planning on storing them for any length of time. As soon as practical after picking, wash the vegetables in cold water or spread them out in the coldest place possible, such as a refrigerator or crisper. This will slow down the respiration rate of the vegetables, thus improving their shelf life and quality.

A good rule of thumb in predicting the maturity of vegetables is to count the number of days between flowering and maturity. This applies to the edible part, such as the tomato or cucumber fruit. Botanically, the edible portions of these vegetables are fruits.

Slicing cucumbers need 14 to 15 days after flowering and are best when they are more than 5 inches long, but still slender and dark green. When sliced, the seeds and seed cavity should still be immature. Pickling cucumbers require only four to five days and are usually picked more than 1 1/2 inches long. All cucumber types should be picked two to four times per week. Never leave over-mature cucumbers on the vines or future production will greatly decrease.

Tomato maturity varies depending on the variety and season of the harvest. Most varieties require 45 to 55 days. Harvest the tomatoes when they reach their respective full colors. Remember, the sugars and other materials which are necessary for developing the full tomato flavor are developed in the last stages of ripening while the fruit is still on the plant.

The best stage of maturity for picking sweet peppers depends upon the purpose for which they are grown. Pick green peppers at full size before they begin to change color. For higher vitamin content and a different taste experience, allow the sweet peppers to develop their final yellow, orange or red color, depending upon the type and degree of maturity. About 45 to 55 days are necessary for sweet peppers to reach the green stage and another 15 days for the fruit to turn red.

Pick eggplants as soon as they attain satisfactory size but before the surface loses its bright, glossy appearance. Dullness indicates over-maturity and loss of quality. Use a sharp knife or pruning shears to cut the stem close to the fruit.

Sweet corn matures in 18 to 24 days after half of the silks have appeared, but high humidity can speed the maturity.

All summer squash types — straightneck, crookneck, zucchini and scallop or patty pan — are harvested and eaten while still young and tender, before the seeds begin to ripen or the rinds harden. Pick them often. Plants cease to produce if some fruits are allowed to reach to full maturity. The winter squashes, such as Hubbard, require 11 to 12 weeks until the fruit are ready while, Acorn and Table Queen squash will be ready in about eight weeks.

In addition to temperatures, other factors affecting maturity of vegetables are day length, rainfall, variety, soil fertility and garden slope.

Bill Lamont is a professor and extension vegetable specialist in the department of plant science at Penn State and can be reached by email at wlamont@psu.edu. 

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