Skip to Content.
Sympa Menu

livingontheland - [Livingontheland] Commonly grown onions

livingontheland@lists.ibiblio.org

Subject: Healthy soil and sustainable growing

List archive

Chronological Thread  
  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Commonly grown onions
  • Date: Fri, 29 Jun 2007 18:47:30 -0600


Adapted from Marianne Riofrio and E. C. Wittmeyer, Ohio State University
Extension, 2000
http://www.uri.edu/ce/factsheets/sheets/onions.html

Commonly grown onions are the mild types, such as White and Yellow Sweet
Spanish, and the more pungent globe types. The pungent onions are better
suited to long-term storage.

The common onion (Allium cepa), one of the most widely grown onions, is
grown from either seed, plants or sets for use as both green onions and dry
bulbs. The home gardener will usually have more success with sets. Any
standard onion variety or hybrid can be used for green bunching onions if
harvested at the proper stage of maturity. Onions can be used as green
onions within 30 days if grown from plants or sets, or 40 to 50 days if
grown from seed. For dry onions from sets or plants, 100 or more days are
required from planting, depending on the variety grown.

The potato, or multiplier, onion and the Egyptian onion are grown from
vegetative parts rather than seed. The underground portion of the potato
onion (Allium cepa var. solanium) is a compound bulb formed from the
segregation of a large mother bulb. Each bulb in the compound bulb produces
6 to 12 plants. The principal use of these onions is the production of
early green bunching onions.

The Egyptian onion (Allium cepa var. viviparum) produces clusters of small
bulbs called bulbils at the top of the seed stalk in late summer. The
bulbils are used to produce very early green onions. Both potato and
Egyptian onions are planted in the fall, overwintered with some mulch
protection, and brought into production in the early spring. These onions
are referred to as "winter onions."

Climatic Requirements:

The onion is adapted to a wide range of temperatures and is frost-tolerant.
Best production is obtained when cool temperatures (55 to 75 degrees F)
prevail over an extended period of time, permitting considerable foliage
and root development before bulbing starts. After bulbing begins, high
temperature and low relative humidity extending into the harvest and curing
period are desirable. A constant supply of adequate moisture is necessary
for best results. For onions started from plants, a light mulch will help
conserve moisture for uniform growth.

An important aspect of onion development is the length of day
(photoperiod). Photoperiod, along with temperature, controls when the
onions form bulbs. Some onion varieties are short-day and form bulbs when
the days are 12 hours or less in length. Other varieties are long-day
plants, forming bulbs when there are 15 or more hours of daylight. The
specific photoperiod of some onion varieties makes them unsuitable for
northern climates, as they will begin to bulb when the plants are too
small. The influence of day length requires that Sweet Spanish and Bermuda
onions be grown from plants rather than seed in the Northeast. Southern
types such as Vidalia do poorly in New England.

Unfavorable growing conditions may result in onions bolting or sending up
flower stalks. If flower stalks should develop, carefully cut them from the
plant immediately or bulbing will be reduced.

Soil Requirements:

Onions grow best in a loose, well-drained soil with high fertility and
plenty of organic matter. Avoid heavier soils such as clay and silt loams,
unless they are modified with organic matter to improve aeration and
drainage. Onions are sensitive to highly acid soils and grow best when the
pH is between 6.2 and 6.8.

Fertilizers:

As with most vegetables, lime and fertilizers are best applied using the
results of a soil test as a guide. Fertilizers of a 1-2-2 ratio (5-10-10,
for example) are generally good for onion production. As the onion plant's
root system is very limited, high soil fertility is essential for good
production.

Establishing the Planting:

Onions should be planted early in the spring as soon as the soil can be
worked. Onion seed is sown 1/2 inch deep, while sets are planted one to two
inches deep. A three-inch plant spacing is desirable. Rows should be 12 to
18 inches or more apart depending on the method of cultivation. For wide
row planting, plants or sets are placed on 3-inch centers. Onions are ideal
for wide row planting, but keep in mind that weeding must then be done by
hand.

Problems:

After the plants are well-established, a mulch will conserve soil moisture,
prevent soil compaction and help suppress weed growth. In windy areas,
small plants must be protected with a windbreak of some type to prevent
serious damage or loss of plants. Weeds, insects and diseases must be
controlled. Thrips, onion maggots, downy mildew, neck rot, pink root and
smut can all harm onion crops.

Harvesting, Curing and Storing:

Harvest onions when the tops have fallen over and dried. On sunny, breezy
days, onions may be pulled and left in the garden for a day or two to dry
before they are taken to a curing area. Curing must take place for the
onions to be stored for any length of time. Cure onions by placing them in
a warm, well-ventilated area until the necks are thoroughly dry. With warm
temperatures, good air circulation and low humidity, curing should be
completed within two weeks after harvest. Onions are best stored in a cool,
moderately dry area in ventilated containers.






  • [Livingontheland] Commonly grown onions, TradingPostPaul, 06/29/2007

Archive powered by MHonArc 2.6.24.

Top of Page