Onions are cool-season vegetables that are
grown mainly for the flavor they add to other foods..
Onions begin to form bulbs based on the day length. Onions can be started from either
seeds, sets, or transplants. Onion seed of both white and yellow varieties
can be sown indoors in flats, in the winter, or early
spring, depending on where you live. In most areas you will need to start your seedlings
indoors. Also, seeds can be sown directly into the
garden, covered with about one-fourth inch of soil and
should sprout between 7- 10 days. If planted thickly, plants can be pulled and utilized
as green onions or scallions for salads or fresh eating
in about 8-10 weeks. However, most gardeners want
to grow an onion bulb as large as possible. To do this, the onion plants must be thinned
until they are at least 2-3 inches apart to insure adequate
bulb expansion. The removed plants can be used
for scallions or you can re-transplanting into another area of the garden so that they
will too have adequate space to enlarge into large bulbs.
In my opinion onion seeds is the least recommended way to start onions.
The other option you have is — Onion Sets. Growing onions from onion sets is probably
an easier way to produce a crop of quality onions,
and in most cases you will be able to achieve better success this way when compared to growing
onions from seed. Sets are small, dry onion bulbs that have been grown the previous year.
They are the easiest for many gardeners to grow.
Buy a bag of sets, push them into damp soil until just
the top is showing and the onion quickly starts growing. They are frequently sold only as
yellow, white or red onions without a variety name.
So if you want to know what varieties your growing,
do not use onions sets. Round onions will produce a flattened onion, and tear shaped
or elongated sets will produce round onion. Larger
sets are best used as green onions while smaller sets are left in the ground to form bulbs.
And then, there is the last option for growing onions – Onion Plants.
The way I usually grow onions and how I would recommend growing onions for the first time.
For large, firm bulbs, plants are best. They were produced from seed in the same year they
are sold.
Plants are available from seed catalogs, garden centers or your local hardware stores. Plant
onions – onion plants — transplants, four to six weeks before the last estimated spring
freeze. Generally plants come in a bundle. Plant the
onions 1″ deep and no deeper, as this will inhibit
their ability to bulb. When you receive your onions transplants,
they are alive, and should be planted as soon as
possible. If your unable to plant these right away, remove the onion plants from the box
and spread them out in a cool, dry area. The roots
and tops may begin to dry out but do not be alarmed, as the onion is a member of the lily
family and as such will live for approximately three
weeks off the bulb. The first thing that the onion will do after planting will be to shoot
new roots. The next most important thing in planting
onions, is choosing the right onion to plant based on
your location. There are three different types of onions. Short-day onions, day-neutral onions also
know as intermediate day onions, and long-day onions
First, the Short day onions Form bulbs with 10 to 12 hours of daylight
They need mild winter climate, usually Zone seven or warmer
Planted in fall, mature in late spring And can be grown in the North, but the bulbs
don’t get as large And then we have the Intermediate or day-neutral
onions These form bulbs with 12 to 14 hours of daylight
Produce nice bulbs in all regions except South Florida or South Texas, these intermediate
onions are ideal for Zones five through six
Planted in fall in mild winter climates and in early spring in northern regions
Then lastly you have the Long-day onions Which form bulbs with 14 to 16 hours of daylight
These are typically grown in northern regions, zone six and colder
Day length is the most important factor in selecting your onion varieties. Long day onions
grow north of a line approximately from Washington,
DC. to San Francisco, short day onions south of
the line and intermediate day length for several miles on either side of this line. Flavor
and pungency are other factors in selecting varieties.
Sweet white onions are generally long-day varieties while the best strong-flavored yellow
onions are intermediate or short day onions. As far as planting goes Select a location
with full sun where your onions won’t be shaded by
other plants. The Soil needs to be well-drained, loose,
and rich in nitrogen; and compact soil affect your
bulb development. You want nice loose, rich soil.
Till in aged manure, compost or fertilizer in the fall before planting. Onions are heavy
feeders and need constant nourishment to produce biggest bulbs.
At the time of planting, you can mix in some fertilizer, too, and side dress every few
weeks until the bulbing process begins.
Are you planting seeds? Onion seeds are short-lived. If planting seeds indoors, start with
fresh seeds each year. Start seeds indoors about 6 weeks before transplanting. Transplants
should be set out 4 to 6 weeks prior to the date of the last average freeze.
Plant onions as soon as the ground can be worked in the spring, Make sure the temperature
doesn’t go below 20 degrees Fahrenheit For sets or transplants, plant 1 inch deep,
with 4 to 5 inches between each plant. Also I plant
them in rows usually about 12 to 18 inches apart. Should you want to harvest some of
the onions during the growing season as green
onions, you may plant the plants as close as 2
inches apart. Pull every other one, prior to them beginning to bulb, leaving some for
larger onions.
Reminder! Do not plant them too deep, or they will not make as large of a bulb
If you have left over onion plants from your bundle, you can plant them in a pot or plant
them in the ground together, like I usually do, and grow them all season long, and harvest
them for “green onions” .
Onion Fertilization and Growing Tips Onions require a high source of nitrogen.
For organic growing like we do, use a rich compost
high in nitrogen. The conventional, non-organic way would be to use a nitrogen-based
ammonium sulfate or ammonium nitrate fertilizer and this should be applied at the rate of
one cup per twenty feet of row. There is no such
thing as an organic all-nitrogen fertilizer. The first
fertilizer application should be about three weeks after planting and then continue with
applications every 2 to 3 weeks. Once the neck starts feeling soft do not apply any
more fertilizer. This should occur approximately
4 weeks prior to harvest. Always water immediately after feeding and maintain moisture during
the growing season. The closer to harvest the more
water the onion will require. For weed control Unfortunately, there is not
any organic product available to assist in weed
control so the only method will be cultivation. That’s right, get on your hands and knees
and pull up the weeds. While cultivating be careful
not to damage the onion bulbs. As the onion begins to
bulb the soil around the bulb should loosen so the onion is free to expand. Do not move
dirt on top of the onion since this will prevent the
onion from forming its natural bulb. So don’t be
alarmed if you start seeing onion protruding from the ground as the bulb expands and enlarges.
Flowering also known as Bolting Most folks want to grow onion bulbs NOT onion
flowers! What causes bulb onions to send up flower stalks? Flowering of onions can be
caused by several things but usually the most common
is temperature fluctuation. If the onion is exposed to warm temperatures, then cold, then
warm again, it will bolt. An onion is classed as
a biennial which means it normally takes 2 years to go
from seed to seed. Temperature is the controlling or triggering
factor in this process. If an onion plant is exposed to
alternating cold and warm temperatures resulting in the onion plant going dormant, resuming
growth, going dormant and then resuming growth again, back-and-forth, the onion bulbs
prematurely flower or bolt. The onion is deceived into believing it has completed two growth
cycles or two years of growth in its biennial life cycle so it finalizes the cycle by blooming.
Flowering can be controlled by planting the right variety at the right time. Use only
transplants that are pencil-sized or smaller in diameter
when planting in early spring or always plant seed.
Onions sets are more likely to bolt, because they were produced the previous year. What can you Do About Flowering Onions? If
you can see a flower stalk apper should you remove the flower stalk from the onion plant?
Probably not…it’s not going to do any difference
for you. Suit yourself but once the onion plant has
bolted, or sent up a flower stalk, there is nothing you
can do to eliminate this problem. The onion bulbs will be edible but smaller. Use these
onions as soon as possible because the green flower
stalk which emerges through the center of the bulb
will make storage almost impossible. Once again, use these onions First! Harvest them,
use them First.
As far as Harvesting And Storage goes, Onions are fully mature when their tops have
fallen over. After pulling from the ground allow
the onion to dry, clip the roots,cut back the tops to about one inch. The key to preserving
onions and to prevent bruising is to keep them in
a cool, dry and separated. Remember to use the onions
that bolted or flowered first, they will not last very long in storage. As a general rule,
the sweeter the onion, the higher the water content, and
therefore the less shelf life. A more pungent onions
will store longer so eat the sweet varieties first and save the more pungent onions for
storage. So, Happy Garddening and Good Luck on Growing
Onions!