The onion has been grown since remote antiquity and its culture and use are noted in our earliest records. It probably originated in middle Asia. The Onion belongs to the Lily Family with such other closely related plants as Garlic, Leek, chives, shallots and welsh onions. It is generally a biennial or long-season annual although some forms such as the ‘Multi-pliers’ are perennial.
The Onion is one of the most important vegetable crops, grown for consumption in the green and mature bulb state, in all sections of the U.S. The more important commercial production areas are in Tex., Calif., N.Y., Mich., Colo., Ore., Idaho, N.J., Wisc., N. Mex., and Minn.
There are many varieties listed in seed catalogues, a number of which are hybrids developed for specific cultural conditions. In general, there are 2 types of onions grown for dry bulbs, the American or pungent and the “foreign” or mild types. Each contain varieties that are yellow, red and white and vary in shape from flat, globular to elongated bottle. With such a wide variation only a few of the more important sorts in each category can be listed.
In the American types ‘Southport Yellow Globe’, ‘Yellow Globe Danvers’, ‘Early Yellow Globe’ and ‘Ebenezer’ which is grown from sets as are yellow varieties. ‘Red Wethersfield’ and ‘Southport Red Globe’ and ‘Southport White Globe’ represent red and white sorts. ‘White Portugal’ is good for pickling. In “foreign” types, ‘White Bermuda’ and ‘Yellow Bermuda’, ‘Early Grano’ and the many strains of ‘Sweet Spanish’ are most important. Varieties that are grown for green onions (scallions) include ‘Japanese Bunching’, ‘Beltsville Bunching’, ‘Multipliers’ and ‘Perennial Tree’.
It is recommended that several reliable seed catalogues be checked for detailed variety characteristics and adaptability.
Onion Soils and Soil Preparation
While onions can be grown on all types of soil, the sandy or silt loams and muck soils, where available, are preferred. For onions, it is important to prepare a well-pulverized seedbed that has been smoothed with a rake or drag. This is especially true if the crop is to be grown from seed.
A soil pH of 5.8-6.5 is optimum. Lower acidity retards growth. The use of well-rotted manure is advisable; 30-40 bu. per moo sq. ft. Fresh manure usually contains weed seeds and may cause a problem in weed control and, therefore, if rotted manure is not available, good compost is preferred. In addition to manure apply 30-40 lbs. of a commercial fertilizer per 100 sq. ft. Incorporate thoroughly into the soil. After the plants are well established a side dressing of nitrate of soda, 3-4 lbs. per 100 sq. ft., is a good practice and yields good results.
Onion Planting Methods
There are 3 methods commonly used in planting onions; by seed, sets and seedling plants. Direct seeding requires a fine seedbed and good moisture conditions. The seed requires from 8-12 days for germination after which some to days to 2 weeks are necessary for the seedlings to become well established. One oz. of seed is needed for 100 ft. of row and the rows are spaced 12-15 in. apart.
Seedling plants purchased from reliable dealers or seeds men are inexpensive and easy to handle. The plants should be stocky with bulbs the size of peas and have bushy roots. Plant distances of 3-4 in. in the row and 12-15 in. between rows. Onion sets, immature bulblets, are used extensively for green onions in the spring and also for mature onions because of their ease of planting. Furrows are opened, the sets placed 3-4 in. apart and then covered with 1 in. of soil. Planting dates for seed and sets, as early as possible, but delay with seedlings until danger of severe frost is past.
Onions require continuous shallow cultivation to control weeds and to maintain soil mulch. A scuffle hoe does a good job. Many commercial growers use a selective herbicide for onions. Again, this is not recommended in the home garden.
When the bulbs have reached mature size and the tops break over, the plants are pulled and placed in rows to dry for 3-6 days. The top is then cut off about 1 in. above the bulb and the bulb is then again spread out for drying for several days before placing into storage. Use crates or netted sacks and a storage that is cool, well ventilated and dry.
Onion Insects and Diseases
Onion maggot is the larva of a small fly. The maggots, in. long, kill the young plants and burrow into the bulb. Starting in early May, apply 3 applications at 7-day intervals of Diazinon, 2 level tablespoons per gal. of water. Onion thrips are small, yellowish, sucking insects which attack the leaves. Dusts containing malathion or Diazinon applied at 7-10 day intervals give satisfactory control. Onion smut, a fungus living over in the soil, attacks the small seedling plants. Avoid soil where disease has occurred. Apply a formaldehyde solution, 1 teaspoon to 1 qt. of water, in seed furrow at rate of 3 qt. per 10 ft. of row. Downy mildew, a fungus disease common during cool wet weather, causes the leaves to turn yellow and die. Dusting at weekly intervals with copper-lime or using a spray of Bordeaux mixture gives satisfactory control. Pink root and neck rot are other diseases that may cause damage but which have no specific control.