Thursday, January 21, 2010

Never Enough Onions

My father and uncles used to say, quoting Hippocrates, "Let your food be your medicine," and onions certainly fit the saying.  They have been highly regarded for medicinal and culinary purposes for millenia.  As medicine, they've been used to treat many complaints such as balding, asthma, burns, insect bites, and to promote longevity.  As food they've been used in everything from soup to dessert.  Because they are so versatile and easy to grow, you should have some in your garden.  In my opinion, you can never have enough onions.

Onions can be started from seed, seedlings or sets.  Seeds should be started indoors at least two months before last frost.  Seedlings and sets can be obtained from local nurseries or by mail order.  Seedlings are onions that have not begun to set bulbs.  Sets are small onion bulbs.  Planting sets is the easiest and fastest way to a crop.

Onions prefer full sun or at least six hours per day.  Soil should be well drained, moderately fertile and moist, with pH between 6.5 and 8.0.  The pH can be determined with a simple soil test.

Planting time depends upon your climate zone.  Onions are a warm season crop, but are best if grown quickly in relatively cool weather.  Hot temperatures and dry soil often induce the plant to go to seed.  The thick and tough seed stalk emerging from the bulb diminishes the quality of the bulb.  Growers in the Deep South often begin planting as early as December in order to harvest in May.  Farther north, gardeners begin planting in March or April in order to harvest in late summer.  Sort periods of freezing temperature and frost will not damage onions unless the temperature drops below 25 degrees F.  Contact your local Cooperative Agricultural Extension Service for recommendations for your area and to help you with testing your soil.

Cultivate the soil and add compost or fertilizer according to soil test results and recommendations.  If you add synthetic fertilizer, do so about two weeks before planting.  Remove weeds and debris.

Onions can be planted in double rows or raised beds.  They can also be planted throughout the garden as companion plants for other vegetables, fruits and ornamental plants.  If planting in double rows, plant the sets about four inches apart.  The double rows should be six to ten inches apart.

If planting in raised beds, plant the sets about 4 inches apart in beds no wider than three feet.  Beds wider than three feet are more difficult to reach into and maintain.

Onions can be planted throughout the garden as companion plants, partnering especially well with members of the cabbage family like broccoli and cauliflower, strawberries, tomatoes, beets, lettuce and roses.  Onions don't grow well together with beans and peas.

Cover the onion set with soil but do not cover any green foliage that may emerge.  Sometimes a late frost can cause the bulbs to rise in the soil.  Rain or irrigation can erode soil away from the bulbs.  If this happens, use a garden hoe to bring a bit of soil over the bulbs taking care not to damage them.  If the tops of the bulbs are exposed, they can be damaged by the sun.

Onions need about one inch of water per week.  Irrigate if rainfall is inadequate.  Over-watering can result in soggy soil causing root rot.

Weed as necessary.

Onions can be harvested at various times.  Green onions with immature bulbs can be pulled when the leaves are about seven inches tall.  If some of your onions are crowding because of being planted to closely, thinning them will provide you with some green onions.  You may harvest them anytime they look big enough to you.  You may be able to allow some to grow to full maturity, when the leaves begin to yellow and drop over.  In any case, it is advisable to harvest onions if they are beginning to show signs of going to seed, thereby salvaging them before they become practically unusable.

Onions have few insect pests.  Root maggots and thrips can cause problems.  Root maggots can be prevented by companion planting the onions as described above.  This prevents the maggots from travelling from bulb to bulb.  If planted in rows or raised beds, consider covering the onions with light and permeable row covers manufactured specifically for crop protection.  Row covers can also prevent birds from damaging the bulbs.  Thrips can be controlled with insecticidal soap or insecticides labeled for onions.

Mature onion bulbs can be stored for future use by cutting off the yellowed foliage and laying the bulbs on sheets of newspaper for about three weeks in a warm, dry place.  This allows the papery covering of the bulbs, called tunics, to dry.  When the tunics are dry, the bulbs can be kept in net bags for several weeks.

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