Most of us have harvested our last produce from the garden for the year. It is now time to find ways to store them to maintain their best quality over the winter months. Here are some suggestions for some produce commonly found in home gardens from Richard Jauron, Iowa State University Extension and Outreach Horticulturist.
Onions should be harvested when most of the tops have fallen over and begun to dry. Carefully pull or dig the bulbs with the tops attached.
After harvesting, dry or cure the onions in a warm, dry, well-ventilated location, such as a shed or garage. Spread out the onions in a single layer on a clean, dry surface. Cure the onions for two to three weeks until the onion tops and necks are thoroughly dry and the outer bulb scales begin to rustle. After the onions are properly cured, cut off the tops about 1 inch above the bulbs. As the onions are topped, discard any that show signs of decay. Use the thick-necked bulbs as soon as possible as they don’t store well. An alternate preparation method is to leave the onion tops untrimmed and braid the dry foliage together.
Place the cured onions in a mesh bag, old nylon stocking, wire basket, or crate. It’s important that the storage container allow air to circulate through the onions. Store the onions in a cool, moderately dry location. Storage temperatures should be 32 to 40 degrees F. The relative humidity should be 65 to 70 percent. Possible storage locations include a basement, cellar, or garage. Hang the braided onions from a rafter or ceiling. Since the temperature in an unheated garage may fall well below 32 degrees F, an alternate storage site will be needed when bitterly cold weather arrives.
Potatoes can be harvested when the tubers are small and immature (“new” potatoes) or when the crop is fully mature. “New” potatoes are dug when the plants are still green and the tubers are greater than 1 inch in diameter. New potatoes should be used immediately, as they do not store well.
Potatoes grown for storage should be harvested after the vines have died and the crop is mature. To check crop maturity, dig up one or two hills after the plants have died. If the skins on the tubers are thin and rub off easily, the crop is not fully mature. Allow the crop to mature for several more days before harvesting the potatoes. When harvesting potatoes, avoid bruising, skinning or cutting the tubers. Damaged potatoes should be used as soon as possible.
After harvesting the potatoes, cure the tubers at a temperature of 50 to 60 F and high relative humidity (85 to 90 percent) for two weeks. The curing period allows minor cuts and bruises to heal. Thickening of the skin also occurs during the curing process.
Once cured, store potatoes at a temperature of 40 F and relative humidity of 90 to 95 percent. Store the crop in a dark location, as potatoes turn green when exposed to light. If storage temperatures are above 50 F, the tubers may begin to sprout in two or three months. When stored below 40 F, potatoes develop a sugary, sweet taste. Sugary potatoes can be restored to their natural flavor by placing them at room temperature for a few days prior to use. Do not store potatoes with apples or other fruit. Ripening fruit give off ethylene gas, which promotes sprouting of tubers.
Winter Squash and Pumpkins
To insure a long life, pumpkins and winter squash must be harvested, cured, and stored properly. Immature fruit are poor quality and cannot be successfully stored. Mature fruit that have been removed from the vine are still alive. Proper curing and storage slows the rate of respiration and prolongs the storage life of the fruit.
Harvest pumpkins when they have developed a uniform orange color and have a hard rind. Mature winter squash have very hard skins that can’t be punctured with your thumb nail. Additionally, mature winter squash have dull-looking surfaces. Harvest all mature pumpkins and winter squash before a hard freeze. A light frost will destroy the vines but should not harm the fruit. However, a hard freeze may damage the fruit.
After harvesting, cure the pumpkins and winter squash (except for the acorn types) at a temperature of 80 to 85°F and a relative humidity of 80 to 85 percent. Curing helps to harden their skins and heal any cuts and scratches. Do not cure acorn squash. The high temperature and relative humidity during the curing process actually reduce the quality and storage life of acorn squash.
After curing, store pumpkins and winter squash in a cool, dry, well-ventilated location. Storage temperatures should be 50 to 55°F. Do not store pumpkins and squash near apples, pears, or other ripening fruit. Ripening fruit release ethylene gas which shortens the storage life of pumpkins and squash. (Actually, the best storage temperatures for most apples and pears is 30 to 32°F.) When storing pumpkins, place them in a single layer where they don’t touch one another. Good air circulation helps to prevent moisture from forming on the surfaces of the fruit and retards the growth of decay fungi and bacteria. Placing pumpkins in piles generates unwanted heat which may result in the rotting of some fruit. Periodically check pumpkins and winter squash in storage and discard any fruit which show signs of decay.
Properly cured and stored pumpkins should remain in good condition for 2 to 3 months. The storage life of acorn, butternut, and hubbard squash is approximately 5 to 8 weeks, 2 to 3 months, and 5 to 6 months, respectively.
Home-grown apples that will be stored should be harvested when they have reached minimum maturity but are not yet ripe. Mature apples are full-size and have a light straw or greenish-yellow undercolor. The undercolor is the “base” color beneath the red blush. The intensity of the red color is not an indicator of maturity. At minimum maturity, apples will be hard and crisp. They will have developed their characteristic flavor but will be somewhat starchy.
Sort the apples that are to be stored. Remove any that are bruised, cut, or show signs of decay. Plan to consume the larger fruit of any cultivar first, saving the smaller ones for later in the season. The larger apples are usually the first to lose their quality and show signs of internal breakdown.
Low temperature slows the respiration rate and preserves good quality. Apples last several times longer at 32°F than they do at 70°F. Most apple cultivars should be stored at 30 to 32°F for optimum storage. However, McIntosh apples should be kept around 36°F. If possible, the storage temperature should remain constant. The freezing temperature of apples is 27.8 to 29.4°F, so it is best not to store apples in unheated locations where the temperature may get too low. Once thawed frozen apples deteriorate quickly, resulting in softening of flesh and loss of texture. Relative humidity must be kept high, between 90 and 95 percent, in a fruit storage area. If the humidity is not maintained, apples dehydrate and shrivel, particularly Golden Delicious.
Apples can be kept well in humid cellars that maintain a cool temperature below 40°F. They also can be stored in unheated outbuildings or garages, in Styrofoam chests, or with hay or other insulating materials piled around them to prevent them from freezing.
If you are interested in harvesting and storing other vegetables here is some additional information.