A member of the genus Allium, which includes onions, shallots, leeks, and chives, as well as ornamental onions, garlic is an underground bulb (also called a head) made up of individual cloves; when you plant a clove, it matures into a bulb. Garlic is divided into two categories, hardneck and softneck, that differ in the size of the bulb, the number and size of cloves, color, hardiness, and storage qualities. Elephant garlic, which is the sort most often used for roasting, is actually a type of leek that has a mild garlic flavor.
Hardneck garlic (Allium sativum ssp. ophioscorodon) produces a stiff flowering stalk, called a scape, topped with bulbils (tiny bulbs) instead of seeds. A single cluster of 5 to 10 large cloves surrounds the hard stalk. Hardnecks are tolerant of cold weather and offer a range of flavors from mild to strong and spicy.
Softneck garlic (Allium sativum ssp. sativum) rarely produces a flowering stalk; the cloves are smaller than hardnecks and are arranged in overlapping layers. A single head may have 6 to 18 cloves or more. The soft, pliable necks are easy to braid into garlic "ropes." Softneck varieties are less cold-tolerant and therefore better suited to growing in regions with mild winters, but they do keep longer in storage than hardneck garlic.
"There are hundreds of variety names for garlic, but there are only 10 major types based on their genetic diversity," says David Stern, an organic farmer and the director of the Garlic Seed Foundation in Rose, New York. "Garlic varieties have been renamed many times as they passed among growers and gardeners, and as a result, many may be identical genetically." The 10 types or groups of garlic are rocambole, porcelain, purple stripe, marbled purple stripe, glazed purple stripe, Creole, Asiatic, and turban among the hardnecks; and silverskin and artichoke among the softnecks. The papery white garlic bulbs available in most grocery stores are artichoke-type softnecks.
Many garlic cultivars have names that indicate where they were traditionally grown or the color of their wrapper, including 'Oregon Blue', 'Chinese Pink', 'Chesnok Red', and 'Spanish Roja'. A study published in 2009 by David Stern with Gayle Volk, Ph.D., of the USDA's National Center for Genetic Resources Preservation in Fort Collins, Colorado, found that no matter what name a garlic cultivar had or which group it belonged to, the color of its papery wrapper and overall bulb size were highly dependent on where it was grown.
This fact helps to explain why so many different variety names exist for genetically identical garlic. It's also an argument for buying locally grown garlic, says Stern. If you buy garlic from a local farmers' market and plant the cloves, what you see at planting time is likely what you'll get when you harvest the bulbs.
Fall planting—September or October—allows garlic cloves to develop a robust root system, though gardeners in southern states may have better results planting in late winter for summer harvest. After planting, a few leaves may sprout from the clove, but they stop growing when cold weather arrives.
Grow garlic in a spot that gets full sun and has loose, crumbly soil. Compacted soil produces irregularly shaped bulbs; soil that retains water, especially during the winter, will cause bulbs to rot. Improve the soil's fertility and texture by working in 1 to 2 inches of organic compost or aged manure before planting.
To prepare garlic for planting, split the bulb into cloves, leaving their papery coverings intact. Choose only those that are firm and free of brown spots and damage." The secret with garlic is to plant the biggest cloves," says nurseryman Ted Biernacki of Ted's Greenhouse in Tinley Park, Illinois, for the simple reason that big cloves develop into large heads of garlic. Plant each clove with the pointed growing tip up and the flat root end down. In areas with mild winters, set the cloves about 1 to 2 inches deep. Where winters are severe, plant the cloves 2 to 4 inches deep. Space them 4 to 6 inches apart in the row with 12 inches between rows. Spread a 2-to-3-inch layer of straw over the planting area to help keep the soil moist and winter weeds in check. Keep the cloves watered for about 3 weeks after planting to aid root growth.
Longer spring days and warm weather help initiate bulb and top growth. Each green leaf represents one layer of the bulb's papery outer wrapper. The leaves will grow a foot or more, and it is critical to keep the soil evenly moist during this period of active growth, because dry soil will inhibit bulb enlargement. In early spring, spray the foliage with dilute liquid fish emulsion. There is no need to fertilize after May, because the extra nutrients will encourage leaf production at the expense of bulb size. When the leaves begin to yellow in summer, hold off on watering to prevent rot.
Cut off the hardneck flower scapes when the looping stems begin to straighten; use raw or stir-fried. Harvesting a leaf or two from each plant to use in place of chives is fine, but don't cut too many, because they supply energy to the growing bulbs. Bulbs are ready to harvest when about half the leaves turn yellow and fall over or when only three or four green leaves remain on the plant. Avoid damaging the bulbs by using a garden fork to lift them rather than pulling them out.
Harvested bulbs must dry thoroughly (a process called curing), or they will rot in storage. Carefully brush away soil, leaving the roots and leaves intact. Lay the garlic out in a single layer in a shaded, well-ventilated spot for 2 to 3 weeks. Once the outer wrapper layers of the bulb feel dry and papery, either braid the stems together (see How to Braid Garlic) or cut them off (leave a ½-inch stub) and store the bulbs in a mesh bag. In general, hardnecks last 6 to 10 months in storage, while softnecks can last up to a year, but homegrown garlic usually disappears into soups, salad dressings, and stir-fries well before then.
The Garlic Roll Call
Garlic sold in grocery stores is often imported from China and treated with a chemical to prevent sprouting, so be sure to buy untreated heads, usually from a local farmers' market or from a nursery. Many heirloom and new varieties are also available via mail order. Of the several hundred garlic cultivars grown in the United States, as many as half are genetically similar, according to a study in the Journal of the American Society for Horticultural Science. Despite the possibility of duplication, these varieties are worth trying.
'Asian Tempest'. Produces 6 or 7 cloves per bulb. Raw, this Asiatic-type garlic is quite hot, but it becomes sweeter and milder when cooked.
'Persian Star'. A purple stripe that produces 8 to 10 moderately spicy cloves and is suited for warmer climates.
'Creole Red'. A Creole-type garlic with 6 to 9 cloves that have a robust flavor.
'Music'. A porcelain variety with 4 to 6 large cloves per bulb and pretty pinkish white wrappers. Perfect for roasting.
'Spanish Roja'. A rocambole with 7 or 8 purple-streaked cloves per bulb and superior flavor when cooked.
'Xian'. This turban variety matures very early and produces 8 to 12 large, plump cloves.
'Inchelium Red'. An artichoke variety with 9 to 18 cloves per bulb; this garlic has a mild lingering flavor that grows stronger in storage.
'California White'. Large bulbs with 10 to 20 mild-flavored cloves. This silverskin variety stores well and is perfect for braiding.
'Chilean Silver'. A pure white silverskin variety with 15 to 18 cloves per bulb.
Garlic Seed Foundation, garlicseedfoundation.info.
Abundant Life Seeds, 541-767-9606, abundantlifeseeds.com
Filaree Farm, 509-422-6940, filareefarm.com
John Scheepers Kitchen Garden Seeds, 860-567-6086, kitchengardenseeds.com
The Garlic Store, 800-854-7219, thegarlicstore.com