|By Chris S. Corby
Editor and Publisher
nions are no exception when it comes to what we can grow bigger and better here in Texas. Unfortunately many gardeners have trouble growing those jumbo, softball-sized onions that most commercial growers produce on a routine basis. To grow them like the pros do, you need to select the right variety, plant at the right time for your area and maintain optimum moisture and fertility.
Onions bulb in response to day length and are classified according to how much daylight they require to bulb. The short day onions need 10 to 11 hours; intermediate varieties need 12 to 13 hours; and the long day varieties need 14 to 16 hours. The day length is just not long enough in South Texas for the intermediate and long day varieties to bulb. Short day onion varieties will produce large bulbs anywhere in the state plus they are milder than the other types. So, unless you garden in Amarillo, where the intermediate and long day varieties will do just fine, we recommend that you stick with the short day varieties commonly referred to as Bermudas. Within that group is the white Bermuda, southern belle, white granex, yellow granex and the famous 1015Y Texas supersweet. Incidentally, “1015” stands for October 15, the optimum time commercial growers plant their onions in the Rio Grande valley.
When To Plant
Next to variety selection, timing is the most critical aspect of growing large, succulent onions. In the spring, the best time to set out transplants is 4 to 6 weeks before the average frost-free date for your area. By planting then your plants will be at the right stage of growth to start bulbing when sufficient day length is reached.
Gardeners in south Texas can plant onion seed in the fall from late September to mid-November and over winter. In central and north Texas, gardeners should avoid planting in the fall as severe cold weather can damage the plants or cause them to break dormancy and go to seed instead of producing a bulb. Sure, you may be able to get away with it if the winter is mild, but most years fall planted onions just won’t work except in south Texas.
Bigger is definitely not better when it comes to onion transplants. Select onion plants that are less than the diameter of a pencil or you will have problems with them breaking dormancy and going to seed as mentioned above. For best results, obtain plants from Texas grown sources, either your local nursery or a mail order grower. Avoid the bulbs and sets you see in catalogs as these are often the long day varieties and will surely disappoint you. You can also grow your own transplants from seed if you have a greenhouse or cold frame.
Onions will grow well in most Texas soils but do best in a well drained soil with a pH above 6.0. The addition of compost will benefit both light sandy soil and heavy clay soil. If your soil is on the acid side (below 6.0 pH) you will need to add lime to raise the pH to above 6.0. Most of you won’t have to worry about pH being a problem unless you garden in East Texas or one of the rare other places in the state that has acid soil. Onions do extremely well in raised beds that also make cultivation easier for the gardener, improve drainage and warm the soil in early spring. Onions really respond to the addition of well rotted barnyard manure. Apply at the rate of 1/2 pound per square foot prior to planting. Also, apply about 1/2 pound of a balanced organic fertilizer per 50 square feet to the bed before shaping and planting. It is important to note that onions have a relatively shallow root system and fertilizer and moisture need to be applied in a rather narrow band around the plants.
We like to plant our onions in double row beds that are about 20 inches wide. The double rows conserve space and make cultivation easier. Whether seed or transplants, we like to plant them pretty thick and then thin them to 3 to 4 inches apart. We eat the thinnings in salads or as green onions and waste nothing.
Once the seedlings or transplants become established you can side dress them with a light application of fertilizer between the rows and water in well. Keep your onions evenly watered during all stages of growth but particularly as they begin to bulb. Remember, they have a very limited root system that must be kept well supplied with nutrients and moisture in order to produce those braggin’ size bulbs we all covet. You will know they are ready to harvest when the tops fall over. Although they can be harvested anytime, this indicates that they have reached maximum size and can be removed for storage and that you should stop watering. Just pull them up, lay them on their sides to cure for a couple of days before storing. Onions can also be left in the ground for a while if the drainage is good and conditions fairly dry.
Several insects, including thrips and cutworms, can damage onions but we hardly ever have any problems with them in our onion patch. If these pests become intolerable you can spray with an approved organic insecticide according to label directions. Most disease problems can be avoided by practicing crop rotation and planting in raised beds.
P.O. Box 129-6129
Carrizo Springs, TX 78834
Willhite Seed Co.
P.O. Box 23
Poolville, TX 76487-0023