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Onions, Garlic, and Shallots

ID

426-411

Authors as Published

Diane Relf, Extension Specialist, Environmental Horticulture, and Alan McDaniel, Extension Specialist, Horticulture; Virginia Tech

 

Table of Contents 

Onions
Garlic
Shallots

 

Onions

ENVIRONMENTAL PREFERENCES

LIGHT: sunny (green onions tolerate partial shade)

SOIL: well-drained loam

pH: 5.5 to 7.0

TEMPERATURE: cool (45 to 60°F) during develop ment; medium hot (60 to 75°F) during bulbing and curing

MOISTURE: moist, but not waterlogged

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CULTURE

PLANTING: Use sets, seeds, or transplants in spring for bulbs and for green or bunching onions. Seeds may be started indoors eight weeks before setting out. Use sets in the fall for perennial or multiplier types of onions.

SPACING: standard 1 to 6 inches x 12 to 24 inches; wide row 4 x 4 inches in rows up to 2 feet wide. Plant close, then thin using thinnings as green onions.

HARDINESS: bulb onions, hardy biennial; green or bunching, hardy biennial; Egyptian or perennial tree and multiplier, hardy perennial

FERTILIZER NEEDS: Apply 3 lbs. 10-10-10 per 100 sq. ft. before planting, use starter solution for transplants, and sidedress four to six weeks after planting with 2 lbs. 10-10-10 per 100 sq. feet (repeat four to six weeks later if needed).

CULTURAL PRACTICES

Onions are often grouped according to taste. The two main types of onions are strong-flavored (American) and mild (often called European). Each has three distinct colors - yellow, white, and red. In general, the American onions produce bulbs of smaller size, denser texture, stronger flavor, and better keeping quality than European onions.

Onion varieties have different requirements as to the number of hours of daylight required to make a bulb. If the seed catalog lists the onion as "long day," it sets bulbs when it receives 15 to 16 hours of daylight and is used to produce onions in Northern summers. "Short day" varieties set bulbs with about 12 hours of daylight and are used in the deep South for winter production. Seed of short day varieties started indoors in January should produce a harvest in June. Seedlings or sets of long day varieties set out in April will produce a harvest in August.

For scallions or green or bunching onions, use sets, seeds, or transplants of standard onions for spring; plant seeds of bunching varieties for summer scallions; or use Egyptian (perennial tree) and the yellow multiplier (potato onion) sets in the fall.

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For bulb production, plant sets or transplants in early spring. Set 1 to 2 inches apart and 1 to 2 inches deep in the row. Thin to 4 inches apart and eat the thinned plants as green onions. Avoid sets more than an inch in diameter as they are likely to produce seed stalks. Too early planting and exposure to cold temperatures also cause seed stalk development. Some people have best bulb production using seedlings or transplants rather than sets. Egyptian tree or multiplier onions should be set in late October or early November. Plant 4 inches apart in rows 1 to 2 feet apart. Distance between rows is determined by available space and cultivating equipment.

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Bulbs compete poorly with weeds due to shallow root systems. Shallow cultivation is necessary; do not hill up soil on onions as this can encourage stem rot. Insure ample moisture especially after bulbs begin enlarging. Onions should be harvested when about two-thirds of the tops have fallen over. Careful handling to avoid bruising helps control storage rots. Onions may be pulled and left in the field for several days to dry, then cured in a well-ventilated attic or porch for one to two weeks out of direct sun. Tops may be left on; if cut off, leave at least 1 inch of the top when storing. Thorough curing will increase storage life.

COMMON PROBLEMS

DISEASES: neck or stem rot, bulb rot

INSECTS: thrips, onion root maggots

CULTURAL: bulb rot from bruising, insufficient drying; split or double bulb from dry soil during bulb formation; very small bulb from too late planting, too dry soil, or planting short day varieties in summer.

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HARVESTING AND STORAGE

DAYS TO MATURITY: 100 to 120 (Mature bulbs)

HARVEST: Harvest green onions when tops are 6 inches tall; bulbs after 2/3 or more of the tops have fallen over. Do not wait more than one to two weeks after this occurs. Allow for thorough drying before storage.

APPROXIMATE YIELDS: 10 to 15 lbs. (per 10 feet of row)

AMOUNT TO RAISE PER PERSON: 10 to 15 lbs.

STORAGE: cool (32°F), dry (65 to 70% RH) conditions; six to seven months

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PRESERVATION: Onions may be stored dry or pickled and canned. They freeze well if chopped and covered with water. For fresh storage, maintain good air circulation. One effective storage method is to place onion in discarded hose, tie a knot and add other onion. When hose is filled, suspend from rafters in storage area.

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GARLIC

ENVIRONMENTAL PREFERENCES

LIGHT: sunny (will tolerate partial shade)

SOIL: well-drained loam, moderate organic matter

pH: 5.5 to 7.0

TEMPERATURES: cool (45 to 60°F) during early development, medium hot (60 to 75°F) during bulbing

MOISTURE: moist, but not waterlogged

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CULTURE

PLANTING: Use cloves which are divisions of the mature bulb. Divide just before planting. Plant early in spring in well-drained soils or in fall and mulch well. Young plants are frost tolerant.

SPACING: standard 3 to 5 inches x 12 to 24 inches (cover to a depth of 1 inch); wide row 3 x 4 inches in rows 12 inches apart

HARDINESS: hardy perennial, grown as an annual

FERTILIZER NEEDS: add 3 to 4 lbs. of 10-10-10 per 100 sq. feet when preparing soil; sidedress one to two weeks after bulb enlargement begins with 2 lbs. of 10-10-10 over 100 sq. feet.

CULTURAL PRACTICES

Garlic, a member of the onion family, may be grown successfully in most Virginia home gardens. There are early (white or Mexican) cultivars and late (pink or Italian) cultivars. The early cultivar does not store well and has poorer quality, but out-yields the later type. Garlic must be planted early in Virginia (March or April) to permit full development. Fall preparation of the soil is desirable so the soil can be fertilized and planted with minimum tillage in the spring.

Garlic is started by planting cloves that are divisions of the large bulb. Each bulb contains a dozen or more cloves; each clove is planted separately. The larger cloves yield larger size mature bulbs at harvest. Do not divide the bulb until ready to plant; early separation decreases yields. Select "seed bulbs" that are large, smooth, fresh, and free from disease.

Plant the cloves 3 to 5 inches apart in an upright position (to assure a straight neck), and cover them to a depth of about 1 inch. Allow 12 to 24 inches between rows. Garlic also lends itself well to a wide row system of planting, spacing cloves 3 to 4 inches apart in rows a foot wide. This requires considerably less garden space for the same yield.

Garlic grows best on well-drained garden loam soils that are fertile and high in organic matter. Gardeners who grow good onion crops can grow garlic. Garlic does well at high fertilizer levels. When preparing soil for planting, apply 3 to 4 lbs. of 10-10-10 fertilizer per l00 square feet. Bulbs will be small if the soil is excessively dry and irregular in shape if the soil becomes compacted.

Harvest bulbs when the tops start to dry usually in August. Place in trays with screens or slatted bottoms, and remove tops when dry. Mature bulbs are best stored under cool, dry conditions.

COMMON PROBLEMS

DISEASES: bulb rot in poorly drained soils

INSECTS: thrips, root maggots

CULTURAL: bulb rot (from bruising, insufficient drying)

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SHALLOTS

ENVIRONMENTAL PREFERENCES

LIGHT: sunny

SOIL: well-drained, sandy loam

pH: 5.0 to 6.8

TEMPERATURE: cool (55 to 75°F)

MOISTURE: moist, but not wet

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CULTURE

PLANTING: Plant individual sets 1 to 2 inches deep in early spring. In warmer climates, plant in fall for winter and spring harvest.

SPACING: standard 4 to 6 inches x 12 to 18 inches or in double rows

HARDINESS: hardy perennial

FERTILIZER NEEDS: Mix 3 lbs. 10-10-10 per 100 sq. feet into soil before planting; sidedress with 2 lbs. 10-10-10 per 100 sq. feet twice during growing season.

CULTURAL PRACTICES

Shallots like a rich, loose soil; mix plenty of compost, decomposed manure or other organic matter into bed before planting. If shallots for planting are sold in clumps, divide into individual sets (bulbs) before planting. Plant as soon as soil can be worked in spring. Plant with pointed tip up; tip should be just below soil line or barely poking through. Mulch or cultivate to keep weeds from competing for moisture. Shallot roots are shallow so cultivation must be carried out with care. Shallot bulbs develop on top of ground. Do not cover with soil.

Shallots have a mild flavor prized by gourmets and are used in the green onion stage or as bulbs. Pull green shallots when they are about 1/4 inch in diameter and store in a cold, moist place for short periods. Mature, dry bulbs are dug after the tops die back, usually in mid- to late summer. Cure in a warm, dry place for about a week. Store in mesh bags in cool, dry conditions. Replant the smaller bulbs or use them first since they do not keep well.

COMMON PROBLEMS

DISEASES: downy mildew, bacterial soft rot, neck rot

INSECTS: onion maggot, onion thrips

CULTURAL: bulb rot from bruising or planting too deeply; tip burn from ozone (air pollutant)

HARVESTING AND STORAGE

DAYS TO MATURITY: 60 to 75 days

HARVEST: Harvest as green onions when tops are 6 to 8 inches high (about six weeks after planting). Side shoots also have little white "button" onions at their base which may be mixed with vegetables, casseroles, etc. Harvest mature bulbs when tops have turned yellow and bulbs are 1 to 1 1/2 inches in diameter. Cut off tops and cure.

APPROXIMATE YIELDS: 10 to 20 shallots per bulb planted; 4 to 8 lbs. per 10 foot row

AMOUNT TO RAISE PER PERSON: 3 to 4 lbs.

STORAGE: cool, dry area (32 to 40°F, 60 to 70% RH); six months or longer

PRESERVATION: store dry or freeze by chopping and covering with water

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Rights


Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.

Publisher

Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.

Date

May 1, 2009


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