By Dr. Leonard Perry, Extension Professor
University of Vermont
Garlic is more than just a flavoring for foods, having many health benefits.
Studies have shown garlic has antioxidant properties, promoting the health of
the heart and immune systems. Allicin, the chemical produced when it is
chopped, chewed, or bruised is a powerful antibiotic. Garlic even has been
shown to reduce cholesterol. Successful growing of garlic starts with choosing
the right "seeds", and giving the correct growing conditions and culture.
Garlic is related to onion, leeks and shallot, only it has a "bulb" composed of
individual wedges called "cloves". It is one of these cloves that you plant in the
fall, soon after the first frost (32 degrees F) but ideally before the first hard frost
(28 degrees F or below). This will give time for roots to form before the ground
gets too cold. Cloves are planted in the fall, as it is the winter cold that is
needed to form the side buds the following year that will grow to make the new
cloves you'll harvest next summer.
There are three types of garlic varieties. The elephant or great-headed garlic is
related closely to leeks, a mild flavor between garlic and onions. It has a large
bulb and few cloves. More common are the stiffneck varieties, with cloves
surrounding a thick central stem that curls as it grows. These have a mild
flavor, are the most cold hardy, but don't store as well as the more common
varieties. Varieties include Rocambole, purple-striped, and porcelain types.
Rocambole types are popular as they adapt to changing weather, and are easy
Most commonly seen are the softneck varieties, named from their stems or
"necks" staying soft when harvested. These are the ones you'll see braided, and
may be called Italian or common garlic. They include the artichoke types you
find in supermarkets, and the silverskins with their very white outer skins and
There are dozens of varieties among these three main garlic types. Buying
locally adapted varieties, either from a local source or based on reliable local
recommendations, is the first key to success.
Garlic traditionally has been grown in hot climates, and you'll need varieties
bred for and adapted to cold climates for northern gardens. Bulbs from grocery
stores shouldn't be used as they may not be the right varieties, and may have
been treated to prevent sprouting.
Plant in well-drained weed-free soil, such as in raised beds. Slightly dry soils
are best, with a pH of 6 to 7. Incorporate plenty of compost in the fall, and you
may not need to fertilize in spring. Or, you may apply a general garden
fertilizer along rows as shoots emerge in spring, then again 3 weeks later. Don't
fertilize after early May to avoid delaying bulb formation.
Water deeply as needed, especially on sandy soils. Stop watering a couple
weeks before harvest.
Garlic roots are near the surface, so if cultivating for weeds keep near the
surface just cutting weeds off there. Be careful to avoid injuring plants.
To avoid potential diseases, don't plant where other onion crops have been the
past 2 or 3 years. Proper soil, mulching, and crop rotation will lessen the
chance of any diseases. Garlic has few if any insect problems.
Large cloves produce the largest bulbs next year. Separate the cloves from
bulbs, keeping the papery husks on, and plant with tips pointing up. Plant 2
inches deep, 4 to 6 inches apart in rows, with rows a foot or two apart. You can
plant small cloves closer, or in patches to harvest
the tops as garlic greens. Figure that a pound of cloves you plant may yield 7 to
Although you won't see growth until spring, roots will begin growing. Mulch
heavily to at least 6 inches deep, such as with weed-free straw, to keep the soil
warmer in fall and winter. Remove mulch in spring, leaving some if desired for
weed suppression. Planting soon enough in fall, and mulching deeply, will
help prevent the seed cloves being heaved out of the ground with spring frost.
Garlic is harvested in mid-summer, early to mid July in the north, but stage of
growth not the calendar is the indicator of when to harvest. You should start
checking the bulbs when the foliage begins to die off. You need to check the
bulbs, not just use the tops dying, as yearly climate conditions can affect the
tops and not the bulbs.
The bulbs are of course not solid like a flower bulb, rather have the cloves
encased in several papery layers called "sheaths". Harvest too soon, and the
cloves won't be segmented yet. Harvest too late and the sheaths will have come
off, leaving just the cloves that are hard to get out of the ground or may even
begin growth. Ideal harvest is when there are 2 to 4 sheath layers present,
which occurs over about a 2-week period.
Once harvested, wash the bulbs and allow to dry for a week or so out of direct
sun. Then trim off the roots, remove the outer dried sheath layers, and then
braid if you wish for storage. Cool (50 to 65 degrees F), dry, and
well-ventilated are ideal conditions for storage. Check monthly to discard any
soft bulbs that may be rotting internally. Set aside the largest cloves for
planting again in fall.