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Timing is everything when harvesting vegetables

  • Martha Proctor
  • Alice B. Toklas once said, "There is nothing that is comparable to it, as satisfactory or as thrilling, as gathering the vegetables one has grown."

    Knowing when to harvest fruits and vegetables is just as important as knowing how to grow them successfully. Some edibles are delicious over a long time period thus lengthening the harvest, others must be harvested at just the proper stage of ripening.

    While it's helpful to keep records for all your garden crops and use average days to maturity as a guideline, the growing information provided on the seed package or catalog assumes long days and warm temperatures. You may find, however, that environmental conditions (rain, wind, pests, etc.) and cultural conditions (water and nutrients, type/pH of soil) can differ from year to year causing the harvest to be unseasonably delayed or even early. If your garden doesn't receive the right combination of soil, sun and water, fruits and vegetables will differ in taste and performance.

    Timing is everything when it comes to harvesting. Fruits and vegetables are living things, and once one is picked, it is cut off from its source of energy — the photosynthetic leaves of the plant. However, respiration, the physiological process during which starches and sugars are converted to carbon dioxide and water, continues and the added flavor that comes from the presence of starches and sugars eventually diminishes.

    Some fruits and most vegetables, such as strawberries, peas and corn, begin to lose flavor and nutritional value as soon as they are picked. Other fruits, such as pears and cantaloupe, will convert stored starches to sugars and other flavor-enhancing compounds in a process called ripening.

    Ripening can only happen for a limited time before the fruits run out of starches. Once a fruit or vegetable runs out of sugars and starches, it begins to decline in flavor, in a process called senescence. At advanced stages, this is accompanied by the production of less-desirable compounds such as ketones, aldehydes and alcohols, all of which hasten the death of plant tissue and decrease the quality and flavor of both fruits and vegetables. This results in wilted leaves, dull or wrinkled fruit skins, or tough or woody stems and stalks in vegetables.

    Gardeners can manage respiration and the freshness of their produce by properly harvesting, handling and storing their produce.

    For maximum flavor and a desirable texture, most vegetables are harvested just before full maturity. Separating the stems and tops as soon as possible helps to maintain flavor. Avoid bruising produce as this invites decay.

    A few guidelines for determining whether your produce is ripe for harvesting include:

    • Color: Many vegetables and fruits change colors as they ripen, such as tomatoes, peppers and bananas. Check the seed packet/garden catalog for information on harvesting and preserving your crops. Two respected resources for edible gardeners are Pam Peirce's "Golden Gate Gardening, 3rd Edition" and Sunset's "Western Garden Book of Edibles."
    • Sheen: Vegetables with a healthy, shiny appearance are usually ready for picking. Except in the case of watermelon, if the skin of the crop is dull, the peak time for harvest may already have passed.
    • Size: Most homegrown vegetables should be harvested and used as soon as they reach a usable size. A common mistake is waiting too long to pick and eat vegetables. Don't delay the harvest until the vegetables look like the ones you'd buy in the grocery store. Your crops will be tender and tasty when they are half-grown or well before they reach market size. If you're unsure, the best way to guarantee you're harvesting at the optimal time is to do a taste test.

    Leafy vegetables like lettuces, chard and spinach quickly wilt so are best picked in the early morning right after the dew has dissipated. Vegetables have their highest water content at that time. This approach or picking on cloudy days or during cool spells also works well for stems and some root crops. Pick lettuces, cucumbers, beans and some herbs early and often to prevent plants from bolting and going to seed. For vegetables in which the fruit or seed bearing part of the plant is the edible part, pick when the fruit/vegetable is as ripe as possible. Whatever you're harvesting, avoid collecting during the heat of the day.

    Most ripe or green-ripe fruit can be ripened off the tree if placed in a brown paper bag with an apple, banana, cantaloupe, avocado, peach or other ethylene-producing fruit. Ethylene is a natural gas given off by ripening fruit, which speeds the ripening process of edible crops exposed to it.

    Crops that mature in late summer and fall have a relatively lengthy harvest period because as the number of hours of sunlight decreases, so do soil and air temperatures. Many fall harvest crops, including most root crops and some of the cabbage family, can be left in the garden into winter and lifted just when they are to be cooked for a meal.

    Early season produce is usually consumed soon after being harvested. Many fall crops will keep for a longer time if preserved or stored carefully. Winter squash, potatoes and onions are best stored in a cool, dark areas of the home. To slow down metabolism in lettuce, peas, corn, broccoli, cauliflower, herbs and summer squash, place the produce in a refrigerator in a ventilated bag into which a slightly moistened towel has been inserted. Or, lock in flavor and nutrients by freezing, canning or making chutney or jam.

    For information about how Marin produce from local farms and ranches is being preserved, come to the Marin Art & Garden Center on Sept. 6 for a presentation by Merrilee Olson, head of Community Action Marin's FoodWorks and the former culinary director for Bon Appetit.