Onions or Cebollas
Almost every Mexican food dish is better if onions are used in the recipe. Most Mexican food recipes require dry, bulb onions. When trying to produce bulb onions in Texas, many gardeners get more flowers than large onions.
If onion seed are planted too early or transplants and sets are used in the fall so that they grow too large before winter, the plants form flowers or "bolt" when temperatures rise in the spring. Bolting is more prevalent after a mild winter.
Acting like a biological computer, the larger-than-pencil-sized onion plant adds up all of the hours of exposure to temperatures of 40° to 45°. When this sum equals that total needed for flower initiation, bolting begins. This process is called vernalization. Fall-seeded and transplanted onions are more susceptible to bolting the following spring if warm fall temperatures promote excessive growth.
Use bulbs with flower stalks early because they will not make bulbs as large as plants which have not formed seed stems. Also formation of the flower stem, whether removed or not, has occurred in the center of the onion bulb. When an onion which has initiated one of these flower stems is stored, the stem tissue decomposes, causing the entire onion to rot.
Onions tolerate temperatures well below freezing. They may be planted from seed, from small bulbs called sets or from transplants. If sets or transplants are used, plant them 3/4 inch deep and 3 inches apart. Do not transplant onions more than 1 inch deep. When seeding onions, plant them 1/4 inch deep.
Because onions are a cool-season vegetable, they grow best during mild temperatures. High temperatures slow vegetative (leaf) growth. The objective is to promote maximum growth in the spring when temperatures rise above 40° to 50° range but before the weather gets hot.
In South and Central Texas, plant seed of short-day onions such as 1015Y (Texas A&M Supersweet), Yellow Granex (known as Vidalia), Grano 502 (yellow), White Granex or Crystal Wax (white) and Burgundy (red) directly into the garden during October or November or wait until February and set out plants.
Seeds sown directly into the garden and covered with 1/4 inch of soil should sprout within 7 to 10 days. If planted thickly, pull the plants and use as green onions or scallions for salads or fresh eating in 8 to 10 weeks. For larger bulbs, thin the plants until they are at least 3 inches apart to allow for bulb expansion.
Fertilizing onion plants is also vital to success. Research indicates that onion growth and yield are greatly enhanced by banding phosphorus about 2 to 3 inches below the seed at planting time. The phosphorus acts as a starter solution which invigorates the growth of young seedlings. Banding phosphorus such as super phosphate (0-20-0) 2 to 3 inches below the seed involves making a trench 3 inches deep, pouring cup of super phosphate per 10 row feet, covering with about 2 inches of soil, sowing seed and covering lightly with 1/4 to inch of soil.
Once established, give onion plants additional fertilizer 19-5-9 as a side application every 4 weeks. Sidedress with ammonium sulfate (21-0-0) if soil is already high in phosphorus and potassium.
This fertilizer encourages larger plants. Each leaf forms a ring in the onion bulb. More leaves mean more rings and larger onion bulbs. Use about cup of the fertilizer for each 10 feet of onion row. Scatter the fertilizer evenly between the rows and water.
Weeds are easy to remove when they are 3 to 4 inches tall. When hoeing weeds and grass, do not work the soil too deeply for it may damage shallow roots. When possible always hand pull weeds to avoid root damage.
Onions may be picked as green onions from the time they are pencil size until they begin to form bulbs. For dry bulb onions, let plants grow larger. Onions are mature when the top of the plant falls over. Physically breaking over the top of onion plants does not increase bulb size. When harvesting bulb onions, loosen the plants in the soil by pulling gently. Let them stay in the garden for 1 or 2 days to dry. Then remove the tops and roots and let them continue drying in baskets or boxes. Green onions can be harvested and used immediately.
Green onions may be eaten fresh or can be chopped and added to salads. Bulb onions may be sliced or diced and used in many recipes or they may be dipped in batter and fried as onion rings.