Commercial Vegetable Recommendations Onions
The average yield of U.S. No. l pungent yellow onions in Michigan is 16.5 tons (660 50-lb bags) per acre. With irrigation and good cultural practices, it is possible to obtain marketable yields of 20 to 25 tons (800 to 1,000 50-lb bags) per acre. Spanish onions from transplants yield 500 to 550 bags per acre. Green onions yield 8 to 10 tons (1,000 to 1,200 boxes) per acre. Most Michigan onions are packed for fresh market, either soon after harvest or from storage.
Types and Cultivars: Onions may be classified in several ways: by shape – flat, round or globe; by color – red, yellow or white; by pungency – mild (sweet or Spanish) or pungent; and by bulbing response to day length – long-, intermediate- or short-day. Most onions grown in Michigan are of the pungent yellow globe type. Only long-day cultivars can be grown from seed in Michigan. Intermediate- or short-day cultivars can be grown successfully from transplants. Seed catalogues often give days to maturity for onion cultivars, but these are relative estimates of normal maturity. Maturity is also influenced by the date of planting, weather during the season and location in the state. In a normal year, early-maturing onions (90 to 100 days) that are seeded in April are ready for harvest by late August. Latematuring onions (110 to 120 days) mature in mid- to late September. Spanish cultivars developed for the northwestern states usually do not mature in Michigan if grown from seed.