University of Vermont Extension
Department of Plant and Soil Science
Fall
News
Article
GROWING GARLIC
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 to peel.
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 strong flavor.
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 10 pounds.
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.
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