University of Vermont Extension
Department of Plant and Soil Science
CHOOSING ONIONS TO GROW
Dr. Leonard Perry, Extension
University of Vermont
you like eating onions and using them in cooking, and have a garden,
should try growing your own. They’re
easy and don’t take up much room. By
growing your own, you can try many cultivars (cultivated varieties)
available in stores, you’ll know just what chemicals and culture
received, and can save some money. There are different types of
onions, so make
sure you choose cultivars of the right type for your region, taste,
are divided into types by short-day, long-day, and day neutral.
These refer to the amount of hours of light
they need to form their characteristic “bulbs” at the base of the
plants in the
soil. Long-day ones require at least 14 hours
of light daily to “bulb up”, so are best suited for the North where
are longer—generally above the 35th parallel (Tennessee and North
northwards). If grown in the South,
they’ll make nice leaves but little bulbs.
onions, on the other hand, are best suited for the deep South where
they only need
10 to 12 hours of light to form bulbs.
If grown in the North, short-day ones will try to form bulbs too
so won’t reach a good size, having too few leaves. Then there are
day-neutral cultivars that
form bulbs regardless of the day length, so can be grown anywhere.
the various types by day length, are groupings by color of skin and
flesh. Red, or purple, onions have a
purplish-red skin and white flesh with some purple coloration which
is lost in
cooking. They are mild to sweet, and can
get quite large. ‘Redwing’ and ‘Ruby Ring’ are a couple of good
cultivars that store well.
onions are the most common type by color, having a brown skin and
flesh. In Britain and British cookbooks
they’re known as brown onions. They
usually are pungent. ‘Copra’ is a good medium-sized, long-day yellow
stores better than most. ‘Ailsa Craig Exhibition’ is very large and
grows well in cool weather. This
heirloom has been around since 1887 when it was introduced in
for the Marquis of Ailsa at Culzean castle.
onions are just that, white both inside and out. Often quite
strong, they’re the ones often
used in Mexican cooking. Sauteed, they
turn a nice brown so are good for onion soup. A mild, day neutral
white that is
good for slicing or frying into onion rings, is ‘Sierra Blanca’.
This was formerly known as ‘Super Star’—an
All-America Selections winner. Cocktail
onions are a very small white type, the one usually pickled in malt
used in stews, and which may be seen as Silverskin, Pearl, Baby,
all three main color groups there are “fresh” and “storage”
cultivars. Fresh onions, also called spring or summer
onions, are best used fresh as they don’t store well (often into
fall), and generally
are sweet or mild. Their skins are
papery, thin, and light in color. Storage onions, also called fall
onions, store well (often into or through winter) and have a strong
They tend to be dark-skinned, with multiple skin layers.
onions are somewhat large to really large, including the large and
Spanish onions. These are mild, produce
lots of fruit, but don’t store well. Bermuda
onions, too, are large and mild, with white flesh. Sometimes sweet
onions are called Spanish or
Bermuda. One of the earliest sweet
onions, shaped like large flattened globes, are the Maui onions from
Hawaiian island. They’re often used for
up to 3 to 4 inches across but really flat like a disc, is the
heirloom cipollini, often found as ‘Borettana Cipollini’. It is
mild with a good flavor, usually
whole or on skewers, and is a long
day cultivar but best grown in warm climates.
few other onions have geographic names, including the sweet ‘Walla
Vidalia. The former is named for its
origin in Washington state, and is suitable for the north. The
Vidalia refers to a group of short-day cultivars
(a main one being ‘Yellow Granex’), grown in that region of Georgia,
was named the state vegetable of Georgia in 1990.
most onions are produced at the bottom of the plant in the soil,
onions are small and produced at the top of the plant instead of
also are known as tree onions, top-setting onions, or walking onions
tops bend down where the bulbs root and grow, thus “walking” through
bed). A variety of these is grown in
Europe as cocktail onions.
type of onion you may see listed, and that you’re probably familiar
stores, are the bunching onions. These
also are called scallions, spring onions, green onions, or
non-bulbing onions. These form bulbs no larger, or only slightly
larger, than the base of the leaves.
While any onion can be harvested early before the bulbs form for
use, there are cultivars just bred for this use. The English
‘Guardsman’ is one of the
earliest, ‘Evergreen Hardy White’ is quite winter hardy, and the
‘Nabechan’ has great flavor.
are related to onions, and can perhaps be described as a bunching
steroids. They don’t form bulbs, and it
is the thick white base (white from being covered with soil) that
eat—actually the lower parts of the leaf sheaths. ‘King Richard’ is
a leek good
for earliness and long white stems, while ‘Lancelot’ is more cold
good for late harvests.
to onions are the mild-tasting shallots.
They’re like onions on the outside, and garlic on the inside, but
either. Some use them as a mild form of
garlic. Grow them, though, like onions. ‘Picado’, ‘Ambition’, and
some good, long-storing cultivars.