Vegetable · Allium
Onions
Allium cepaA pantry staple that bulbs up in response to day length, so choosing a type suited to the local latitude matters more than exact timing. Sets are the easiest, most forgiving way to start, skipping the fiddly seedling stage entirely. The one rule: match your onion type to your day length for full-size bulbs.
Sow depth
¾ in (just covering the set)
Spacing
4 in · rows 12 in
Sun
Full sun
Germination
14–21 days to shoots
Time to harvest
90–120 days
Difficulty
Easy
When to sow onions
- Sow from about 4 weeks before your last expected frost until about 2 weeks after your last expected frost.
Plant sets, tip up — push each small bulb gently into loose soil.Leave the very tip poking just above the soil surface.Space evenly along rows so bulbs have room to swell without crowding.
Weed constantly — onions have thin leaves and hate competition.Water regularly while bulbs are forming, then taper off as they mature.Stop watering once tops begin to yellow and flop over naturally.
Wait for the flop — lift once most tops have bent over and dried.Ease bulbs out with a fork rather than tugging on the necks.Cure in a warm, airy spot for two to three weeks before storing.
Companion plants
Onions mask the scent that carrot fly hunt by, so interplanting the two confuses both pests.
Watch out for
Onion fly — Maggots tunnel into bulbs, especially in cool, wet springs. Rotate beds yearly and remove any wilting plants promptly.