How sweet it is – Noonday Sweet Onions, that is. You don’t have to live in Noonday, Texas to grow your own crop of tasty onions, though. Several factors are involved in producing a successful onion crop. The first factor for success is planting the right varieties. Onion varieties are classified as short-day, long-day and intermediate. Plant the wrong type, and you won’t get a bulb! Short-day onion varieties are the best for our area, although intermediate types will also produce bulbs here in northeast Texas.
One of the more popular onions adapted for our area is the 1015Y or Texas SuperSweet onion, developed by Texas A&M for the Texas onion industry for disease resistance and good size. A bonus was the incredibly mild flavor of this onion. Home gardeners have reaped the benefits of A&M’s research since this is a great variety for backyard gardens. Other varieties for our area include Yellow and White Granex, White Bermuda (also called Crystal Wax), Grano 502 (literally mother of all the sweet onions) and Red Burgundy. Sweet Red and Cimarron are 2 popular intermediate types.
Timing of onion planting is also important. Short day types are planted late January through mid-February, while intermediate types can be planted from early February through early March.
When buying onions, don’t grab the bundles with the fattest plants. The best size transplant is about the size of a pencil or slightly smaller. Any bigger and they may bolt, or flower, resulting in a hollow center and shorter shelf life. Don’t be concerned if they look a little dried. The onion is a member of the lily family and will live for approximately three weeks off the bulb. The first thing that the onion will do after planting is grow new roots.
Onions prefer a fertile, well-drained sandy loam. Make raised beds if your soil is poorly drained to reduce the impact of drenching rains and help warm up the soil more quickly in the spring. Raised beds allow the soil to dry quickly, which is important when the bulbs are nearing maturity. A raised bed of soil 4 inches high and 20 inches wide will allow you to plant two rows of onions down the bed.
Some east Texas soils might be too acidic for good onion growth. If a soil test indicates a soil pH below 6.0, add lime to bring the pH between 6.0 and 6.5.
Early onion growth and yield is promoted by banding a fertilizer rich in phosphorous 2 to 3 inches below transplants at planting time, and plant the transplants so their roots are not touching the fertilizer band.
Set the plants approximately 1 inch deep, 4 inches apart, and 4 inches from the edges of the raised bed. If you want to harvest green onions during the growing season, set transplants 2 inches apart and gather every other one before they begin to bulb.
If you are after large onions, keep this fact in mind: for every leaf there will be a ring in the onion. The larger the leaf, the larger the ring will be. Onions will first form a leafy top, and then, once the proper day length arrives, bulbs will begin forming. Steady soil moisture and adequate fertility during the growth phase are needed to keep those plants growing more leaves.
Mulch will help conserve water, and a drip or soaker hose down the row is a good way to keep the soil moist. The most critical time for water is from bulb initiation until they begin to mature.
Soils rich in nitrogen will produce bigger plants and bulbs. Organic fertilizers high in nitrogen, like cotton seed meal, should be worked into the soil when the beds are made. Side dress with supplemental nitrogen about 3 or 4 weeks after transplanting, and continue monthly until the neck of the bulb starts to feel soft. This should happen about 4 weeks before harvest.
Do not pull soil from around the bulbs to make them larger – it does not trigger bulbing or increase bulb size, but can result in sunburning which turns the top of the bulbs green.
When onions are mature, they develop a soft neck and the tops will naturally begin to fall over. At this time, withhold water to let the bulbs properly cure and dry. “Walking down the tops” does not hasten maturity, as some farmer fables claim, and actually can reduce yields.
Pull onions when they are ready for harvest and cure them in a dry place for several days. After curing, clip the top, leaving about 1 inch of stem attached to the bulb, and let them cure a few more days to help prevent rot organisms from entering.