Days to maturity are from date of transplanting.
Culture: Start indoors in Feb. or March and transplant out in spring almost as soon as the ground can be worked. Set 4–6" apart in trenches in well-dug beds with generous quantities of organic matter. Avoid transplanting next to grass strips; slugs love to dine on tiny allium seedlings. Irrigate seedlings whenever the topsoil dries out.
Onions are day-length sensitive. Long-day types are for northern latitudes. The earlier they are set out, the more chance they have to make top growth while the days are lengthening. The more top growth, the greater the bulb size. After summer solstice they begin bulbing.
After half the onion tops fall, push over the remainder and harvest within a week. Field-cure in the sun about 10 days until dry, covering with a tarp in wet weather. Curing is essential for long storage. Hang sacks in a cool dry well-ventilated place, periodically removing sprouting or rotting bulbs. Onions survive light frosts. When it begins to warm up in spring, put your remaining storage onions in your refrigerator crisper. Most will keep without sprouting until your new crop is ready.
Minimum germination temperature 50°, optimum range 60-70°, optimal temp 68°. Emergence 13 days at 50°, only 5 days at 68°, 99% normal seedlings at 68°. We discourage the use of bottom heat because onions germinate poorly in temperatures above 70°.
We do not hold over hybrid onion seed because of precipitous decreases in germination. Onion seed is short-lived. Retest 1-year-old seed before using. Discard anything older.
Onion sets and plants are available from Moose Tubers.
Diseases: PB: Purple Blotch, PR: Pink Root