Moisture range
28–48%
Days to maturity
90–110
Light
Full sun
Growing Degree Units
1700 · base 40°F
When to plant onion in your zone
Indoor-start, transplant and harvest dates calibrated to your climate.
Growing notes
Onions are shallow-rooted and require constant moisture for proper growth. Curing is essential if you want to store onions.
Harvest signs
when about half the tops are falling over and dry
▶Planting reference— Depth, spacing, pH, light
▶Pests & diseases— onion maggot, onion thrips, fusarium basal rot, purple blotch, +1 more
Common pests · 2
Common diseases · 3
Fusarium basal rot: brown and watery rot spreading from the base up to the leaves, brown stem plate at the bottom, leaves can wilt or curl, turn yellow, or die from the tips downward ↗
Purple Blotch: small water-soaked lesions on the leaves or stalk with white centers, spots enlarge and form concentric rings that are brown to purple in color with a red or purple margin surrounded by yellow ↗
Black Mold: black discoloration of tissue, blackening at the neck, streaks or spots of black on or beneath the outer scales, black discoloration in bruised areas ↗
Companions & antagonists
Plant near:CarrotLettuce
Keep apart from:BeansPeas
Common questions
How much water does onion need?
Onion is water-sensitive — shallow roots and a steady thirst. Keep soil moisture in roughly the 28–48% range and don't let it dry out fully, or growth stalls and leafy crops turn bitter.
Can I grow onion in a raised bed or container?
Yes — onion does well in raised beds and is happy in a decent-sized container too, as long as drainage is good.
Does onion come back every year?
No — onion is an annual. It completes its life in one season, so you replant it each year.