Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, January 7, 1993 TAG: 9301060093
SECTION: CURRENT PAGE: NRV-6 EDITION: NEW RIVER VALLEY
SOURCE: Joe Hunnings/staff
DATELINE: LENGTH: Medium
CONSIDER CONTAINER-GROWN ONION SETS
Gardeners who start their onions from seed can take advantage of a successful technique of growing onion transplants in pots.Container-grown onion plants offer several advantages over field-grown transplants and sets.
They have a large root system that immediately begins to grow when set out.
When such plants are compared to the standard, bunched transplants normally available, the actively growing plants grow faster, produce larger bulbs and have less chance of bolting or producing flowers (which reduces bulb development).
Although planting onion sets (small bulbs) is often the easiest way for home gardeners to grow onions, seed-grown transplants are more economical and one can obtain a much wider range of varieties.
Onion sets also need to be selected carefully for a good crop; bulbs of 1/2-inch in diameter are preferred.
Bulbs under this size may lack vigor, while larger ones often go to seed without providing bulbs.
Pot-grown transplants should be started in January.
When most of the plants are about six inches high, set them in the garden at least four inches apart to allow for adequate bulb expansion.
Transplant as soon as possible after the plants reach six inches in height to ensure root establishment before optimum bulbing conditions occur.
Pot-grown onion transplants should be planted only about an inch deep so all roots are covered and the main crown is partially covered.
In each pot, there will be very small plants and larger ones - plant them all.
The smaller plants may mature later so this placement facilitates harvest.
To insure production of maximum-sized onions, fertilize onion plants. This is vital to success.
Start by incorporation of from one to 2 1/2 pounds of 5-10-10 fertilizer per 100 square feet of garden area.
Research indicates that onion growth and yield can be enhanced by banding phosphorus from one to three inches below transplants at planting time. The phosphorus acts as a starter solution to invigorate the growth of the plants.
Banding phosphorus, such as super phosphate (0-20-20), two to three inches below the plant involves making a trench or planting furrow 4 inches deep in a raised planting bed, distributing one-fourth of a cup ([-pound) of superphosphate per 10 row feet, covering the phosphate with two inches of soil, then planting the transplants.
Because onions are heavy feeders, once the plants are established they should receive an additional application of fertilizer, such as one-eighth to one-fourth of a pound of 10-10-10 per 10 row feet, as a side dressing.
Onions require several months to mature, so plant them in a location that will not be needed for the rest of the season.
Also, don't plant onions where they may be shaded later by larger plants, such as tomatoes or corn. Shading decreases growth rate and, subsequently, bulb size.
Provide onion plants with a constant supply of water, especially during bulb enlargement. Taper off irrigation when onion tops begin to yellow, approximately three months after planting. Withering, yellowing tops indicate that the bulbs are reaching maturity and will be ready to harvest after the tops fall over.
Joe Hunnings is the Virginia Cooperative Extension Service agent for agriculture in Christiansburg. If you have questions call the Montgomery County extension office at 382-5790.