Garlic is an easy-to-grow and rewarding crop for the home gardener, and a relatively low-maintenance and profitable crop for the market farmer. It responds very well to organic management practices!
Garlic is widely adapted throughout much of the United States. Here in southern Oregon, our garlic thrives in temperature extremes from 0 degrees Fahrenheit in the midst of winter to 105 degrees around harvest time in July. In general, hardneck varieties will perform better in colder northern climates, and softneck varieties will perform better in warmer southern climates. In Oregon and other moderate climates, both types will do equally well. For the plant to vernalize (be subject to sufficient cold in order to induce bulbing), garlic requires cold temperatures for 1-2 months during the winter. Cold winter weather (temperatures below 40 degrees F) also makes garlic plants more vigorous, and improves their flavor. Garlic is rarely killed by extreme cold unless a sudden cold snap kills back early growth. For this reason it is important not to plant garlic too early in extremely cold areas, thus subjecting the vigorous new growth to killing freezes. Spring and summer weather needs to be generally sunny and warm, although garlic grows well in the maritime regions of the northwest if planted in a location with plenty of airflow and exposure to the southern sky. Too much summer heat is rarely a problem if garlic is kept well watered. In general garlic is about as adaptable a crop as you can plant!
Good soil is important to growing a quality garlic crop. Garlic is happiest in well-drained, fertile soil with abundant organic matter. Loam or sandy loam is best, but most soils will produce well with moderately high levels of organic matter. Garlic is best adapted to soil pH levels between 6 and 7, although it will tolerate soil pH of between 5.5 and 7.5 with reduced yields. It is always best to grow garlic in soils that are managed organically to increase organic matter content and decrease disease build up through cover cropping, crop rotation, and the application of good quality compost or aged manures.
Garlic is propagated by planting cloves. Each clove will develop into a bulb. For the best production, cloves are planted directly into the ground in the fall, four to six weeks before the ground freezes. This can be as early as late September in the north, or as late as November or even December in parts of California. Here in Oregon, and throughout much of the country, October is the ideal month for planting. Planting four to six weeks before heavy frosts allows for root systems to develop with minimal top growth. Garlic can also be planted as soon as the ground thaws in the spring with diminished yields. Plant individual cloves with the scab end down and the pointed end up, one to two inches deep in well-worked beds. Space plants six inches apart with 12-24” between rows. Intensive raised beds can be planted as close as 8” between rows if adequate fertility is provided. Since the largest cloves from the largest bulbs generally will produce the largest bulbs these are the best to plant.
Care During the Growing Season
The most important care for your garlic is to keep it well weeded, watered, and fertilized. We thoroughly weed our garlic fields at least once in early Spring and again in the Summer. It is also important to plant garlic into a weed-free bed in the fall, to give your new plants a head start on competition. Some growers use mulch to help with keeping weeds in check. If you choose to mulch it is best to add it only after a good Spring weeding. Garlic that is mulched all winter can rot and take too long to start growing in the Spring due to cold soil. Once Summer starts most garlic growers remove the flower stalks (or scapes) of hardneck garlic as soon as they emerge in order to focus the plant's energy on the bulb. This is not strictly necessary, although the scapes also make a tasty early summer addition to soups and other dishes.
Water and Fertility
Maintain even moisture during the growing season. Luckily, in most of the United States, rain provides all the water garlic needs from October to April or May. Here in Oregon, we irrigate our garlic once in the Fall after planting and then for two months in May and June. Do not water garlic during the two weeks before harvest as it is important for the plant to begin its drying and curing in the soil before digging. Using a deep mulch in the early summer will help to conserve moisture in the soil in hot and dry climates.
Garlic is a heavy feeder, and as such it benefits from an application of good organic fertility. We pre-fertilize our garlic in the fall with an application of aged manure to the soil before planting. We fertilize again in the spring once vigorous growth has begun and apply foliar sprays as necessary until bulb formation begins in late spring.
Pests and Disease
For the home gardener, garlic is generally a disease-free crop. Crop rotation to avoid disease build up and care in limiting over-watering should control most disease problems. Our major garlic pest is the gopher. These are best controlled with traps, crop rotation, and the encouragement of nesting sites for owls and other birds of prey.
Garlic bulbs are harvested in early summer in areas where the garlic is fall planted, and in mid to late summer in areas where it is spring planted. Harvest is usually done as the plants start to die back and five-seven leaves remain green. We harvest our fall planted garlic in early July. Garlic should be gently loosened with a digging fork and then removed by hand.
Once the bulbs are harvested, they need to be dried to ensure optimal curing and thus long-term storage. Dry garlic by tying the bulbs into bunches of ten to fifteen bulbs and hanging them in a dry, shady place with good air circulation. Allow several weeks for drying, and then clean the bulbs by peeling off a minimal amount of the outer layers to expose a clean bulb. Garlic will store best if the stems are left long, however for ease of packing, after drying the stems can be cut about an inch long, and root hairs can also be trimmed to give a neat appearance.
Store your garlic in a cool, dry place in breathable bags to allow air circulation. Your garlic should keep from four to twelve months depending on variety and conditions.
In general, one pound of planted garlic yields four to eight pounds of harvested bulbs. There is tremendous variation in yields depending on soil quality, irrigation, weed competition, and of course the quality of seed garlic planted. The best seed produces the best yields!