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  A Publication of UVM Extension's Vermont Vegetable and Berry Program

Growing Garlic

by Vern Grubinger
Vegetable and Berry Specialist
University of Vermont Extension

For thousands of years garlic has been used as food, a spice, and a medicine. Recently it’s been used as a pest repellent, too. Garlic probably originated in central Asia, and was then brought to the Mediterranean area and Europe. By the early 1700s it found its way to America.

Types of Garlic.  There are two main types of garlic. Stiffneck, hardneck or topset garlic plants send up a false flower stalk in the spring called a scape. Stiffneck garlic bulbs usually contain five to seven large cloves. Softneck garlic plants do not produce a scape, and softneck bulbs generally contain a dozen or more relatively small cloves. Elephant garlic is not a garlic at all, but rather, a member of the leek family. It produces large bulbs with very few cloves, usually three or four.

Birds and the Bees.  Garlic, like potatoes, is multiplied by vegetative reproduction rather than by sexual reproduction (seeds). Individual garlic cloves are planted and they each produce a bulb in which the cloves all have the same genetic makeup as the original clove. The scape is called a false flower stalk because it does not produce seeds; instead, it develops small bulbils at the top. These can also be used for vegetative production.  However, it takes several years of growth for them to develop into marketable bulbs.

Varieties.  Garlic grows well in many different soils and climates, but only varieties that are hardy and adapted to the Northeast will perform well here. Supermarkets are likely to sell garlic varieties that were grown in warm climates with long growing seasons, so they may not grow well in this area. The most promising sources of well-adapted varieties are garlic growers in your area and seed catalogs that specialize in serving the Northeast.

It’s a good idea to start by ordering several varieties and plant them on a small scale to evaluate their performance under your growing conditions. Save the largest and healthiest bulbs for building your own planting stock. Be aware that it may take several years for a variety to adapt to new growing conditions.

The naming of garlic varieties is pretty much a free-for-all. In other vegetatively propagated vegetable crops like potato, asparagus, and sweet potato, for example, there is a fairly rigorous process of naming and maintaining variety lines. But with garlic, there’s been a lot of creativity in naming varieties because much of the seed stock has been developed and maintained by private individuals. These folks can call their garlic anything they want. As a result, some garlic varieties with different names are actually pretty much the same thing, and some varieties with the same name may exhibit more differences that you’d expect. Since ‘true’ varieties don’t really exist with garlic, the different types are often referred to as ‘strains.’

Why Fall Planting?  One nice thing about garlic is that it’s out-of-synch with most other crops. Instead of contributing to the heavy planting workload of early-season, garlic cloves get planted in the fall. That’s because garlic requires a cold treatment of 40 degrees F for about 2 months to induce bulbing. Garlic can be planted in the spring, but it should be refrigerated first or planted early enough to get a natural cold treatment. It’s my observation that spring plantings don’t tend to size-up as well as fall plantings.  Just for kicks, I once planted garlic in the spring without a cold treatment. The result was rather small ‘bulbs’ that contained a single, round clove. They were great for cooking but not so good for yield and useless for ‘seed’ saving.

The date of planting garlic in the fall should allow enough time for good root growth but not enough time for leaves to emerge from the soil. Those leaves would just get winter killed unless they had plenty of consistent snow cover.  In most areas of the Northeast, the best time to plant is October. To prevent winter injury and heaving of cloves from the soil, plantings should be planted 3 to 4 inches deep, oriented with the root end down. Heavy mulching with straw can be helpful, but isn’t necessary unless you plant clover more shallow. Mulch can help to suppress weeds and maintain moisture, but in a wet year it can exacerbate soil-borne diseases and it should be pulled away from the garlic rows early enough to allow soil drying.

Spacing of garlic cloves has more to do with a grower’s cultivation system than anything else. Often, garlic rows are spaced 6 to 8 inches apart, with several rows to a bed, so as to accommodate cultivation equipment like shovels, basket weeders, and/or hand hoes. Some people plant into beds covered with black plastic to help control weeds. A propane torch, bulb planter, or some type of dibble can be used to make evenly-spaced holes that are large enough to plant through. Usually in the spring some hand work is needed to help a few wayward shoots find their holes.

Growing on.  Garlic grows best when soil pH is in the range of 6.2 to 7.0. If your soil test lab doesn’t offer garlic recommendations, use the P and K recommendations for onions, and incorporate fertilizers prior to planting. Compost, well-rotted manure, and/or leguminous cover crops should be incorporated prior to planting to provide a portion of the crop’s nutrient needs, and to enhance soil health. Apply a sidedressing of about 30 pounds per acre of nitrogen when tops are about 6 inches high.

Garlic is not very competitive, so good weed control is critical. If mulch is not used, cultivation should be shallow so as not to damage any roots. Irrigation should be applied frequently during dry periods to ensure good growth.

Bulb formation is initiated in response to the longer days and warm temperatures of late spring, in May or June. Around the same time, the scapes of stiffneck and elephant garlic develop. These should be removed to retain the plant's resources for bulb formation. The scapes are edible and can be harvested and sold as a spicy green vegetable. They freeze well for later use.

Harvest and Handling.  Garlic is usually harvested soon after the lower leaves of healthy plants begin yellowing from the tips on down, in July in most locations. The ideal timing of harvest is when the bulbs attain maximum size but the cloves have not started to separate. Separated bulbs store poorly, although some separation is desirable in seed stock since it makes separating the cloves easier. It’s a good idea to test dig a few bulbs and cut them in half perpendicular to the cloves to see what stage they are at before starting to harvest.

Undercut the bulbs to make it easier to remove them from the soil. Allow bulbs to air-dry where they are protected from the sun, which may scald them. A well-ventilated barn is ideal. Thorough drying is essential for good storage, and this will take several weeks.

Once cured, rub or brush soil off bulbs, clip the roots, and braid or remove tops. Garlic can then be kept for a several months in mesh or paper bags in a ventilated area with cool temperatures, such as some barns or basements. However, for longer periods of storage, the temperature held just above freezing with humidity around 50 to 65 percent.

Published: August 2005
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