At a grower meeting, Dr. George Wilson at NC State University addressed the subject of harvesting and post-harvest handling of vegetables. He said once you harvest a vegetable it’s at its highest point in quality; what you do after that can only slow its continued deterioration.
Think about the myriad vegetables that growers harvest and handle during a growing season. The grade standards for all vegetables can be accessed at ams.usda.gov/grades-standards/vegetables.
The number one consideration is to harvest crops of the highest ultimate eating quality. In wholesale marketplaces where shipping and shelf-life considerations come into play, vegetables may be picked before they reach peak eating quality (maximum flavor and nutrition). Local roadside stands and farmers markets have a distinct advantage in harvesting vegetables nearer their peak quality.
Most vegetables attain their best eating quality when allowed to ripen on the plant, but often this peak quality is reached before the vegetables are fully mature (i.e., cucumbers, squash, okra, sweet corn, peas and beans). As a result, sometimes a new grower may fall into the “bigger is better” mindset and allow crops to stay on the plant too long.
Most seed catalogs list days to maturity for crops whether direct seeded or transplanted. While this may be helpful, especially when scheduling seed starting dates, succession crops, etc., it’s not always reliable for calculating precise harvest dates. Other factors can influence harvest date, including soil fertility, precipitation and temperature. As a result, actual “days to maturity” may vary from year to year.
Almost all vegetables are best when harvested early in the morning. Overnight, vegetables regain moisture they lost during the day, and starches formed during the day may be converted to sugars during the evening. These traits make morning-harvested produce crisper, juicier and sweeter. If you cannot harvest in the morning, produce should be kept out of direct sunlight and cooled as soon as possible to slow deterioration. When it’s hot out, remember to be gentle with the plants while harvesting. If vegetables are not easily removed when twisted or pulled, use a knife or hand pruners. Finally, frequent picking is essential for prolonging the harvest. The plant’s goal is to reproduce; therefore, if its fruit fully mature on the plant, there’s no reason for it to continue flowering, which means fruit production will stop.
- Snap Beans: They can be machine- or hand-harvested. It’s important to harvest while pods are still tender, before the enlarging seed can be seen through the pod. Pods are ready when they break easily with a “snap.” To harvest, break off the stem above the cap.
- Beets: Roots should be 1.5 to two inches in diameter. Any larger, they may become woody. Tender beet greens (six to eight inches long) may also be harvested and eaten. Fall-planted beets should be harvested before the first moderate freeze. Harvest spring-planted beets before hot weather.
- Cantaloupe: If you gently pull and the fruit separates easily from the stem, it’s fully ripe, at its best eating quality and is called full-slip. Surface netting turns beige and the blossom end becomes soft and smells sweet. Half-slip is when resistance is experienced when putting pressure on the stem attachment; it’ll give you longer shelf-life.
- Sweet Corn: Harvest when the husk is still green and the silks are dry and brown. Kernels should be plump and tender. Pick in the early morning and cool the ears immediately after harvest. Store as close to 32º as possible in a moist environment.
- Cucumber: Begin harvesting when fruits are about two inches long up to any size, but before their flesh becomes bitter, seeds begin to harden or skins begin to yellow. Pickling types should be harvested between two and six inches in length, while slicing and burpless types are typically picked between six and 10 inches long. Pick as frequently as necessary to avoid oversized fruit and to encourage continued production. Harvest by cutting stems with a sharp knife or pruners.
- Eggplant: Harvest any time after they’ve reached sufficient size. They should be removed from plants before the flesh becomes tough and seeds begin to change color and harden. Fruit should be large, shiny and uniform in color. They’re ripe when the side of the fruit is pressed slightly with the thumbnail and an indentation remains. Harvest by cutting stems with a sharp knife or pruners.
- Dry Bulb Onion: Harvest when about three-fourths of the tops have fallen over. Remove tops by cutting one to 1.5 inches above the top of the bulb. Thoroughly air-dry bulbs in a shaded area before storage. Store dry bulbs in shallow boxes or mesh bags in a cool, well-ventilated place. Ideal conditions are 45º – 55º and 50% – 60% humidity.
- Peppers: Harvest sweet peppers when they reach full size, the fruit walls are firm and the peppers are still in the green or yellow state (or allow them to ripen further for red or orange peppers). When harvesting, cut the stems instead of pulling to avoid breaking branches. Bell peppers can be left on the plant to turn color; however, they should be picked as soon as they change to the desired color.
- Spinach: Harvest dark green, tender leaves that are three to six inches long by picking or cutting individual leaves. Start by picking the outer leaves and harvest the newer leaves as they reach the desired size. Whole plants may be harvested by cutting just above the crown or growing point. Remove the petioles or leaf stems if they are too large and fibrous.
- Summer Squash: For optimum quality, harvest while fruits are tender and still have a shiny or glossy appearance. When conditions are favorable, harvest the crop daily or every other day. Harvest crookneck and straightneck varieties when the fruit is 1.5 to two inches in diameter. Harvest zucchini when the fruit is seven to eight inches long and scallop types when they are three to four inches in diameter. Squash can be harvested at smaller sizes for extra tenderness.
- Winter Squash: Harvest when they have very hard skins that cannot be punctured with your thumbnail and the fresh, bright, juvenile surface sheen changes to a dull, dry-appearing surface. Harvest only solid, mature pumpkins with deep orange color. Harvest acorn squash when the spot contacting the soil has turned from pale yellow to orange. Cut the fruits from the vine and leave a generous stem. Do not injure the rind or break off the stem as decay fungi can attack through wounds. Do not harvest or handle wet fruit or allow harvested fruit to get wet. Cure by maintaining storage temperatures from 80º – 85º with 75% – 80% humidity for approximately 10 days. Store the fruit at 50º – 55º and 50% – 75% humidity with good ventilation.
- Tomatoes: Pick fruit when it’s fully vine-ripened but still firm; most varieties are dark red, but many other colors are available. Ideal storage conditions depend on the maturity stage of picking. If tomatoes are picked at mature green, store them at 66º – 70º with 90% – 95% humidity, which encourages uniform ripening. Temps above 81º reduce intensity of red color and shelf-life. Green tomatoes are chilling sensitive. Below 55º, fruit may develop chilling injury. Red tomatoes are safe to store at 50º; however, flavor and aroma may be negatively affected compared to storing them at 55º.
- Watermelon: The vine tendril closest to the fruit dies and turns brown when ready to harvest. The underside of the fruit will turn from white to a creamy yellow. Finally, the skin loses its gloss and becomes dull.
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