Growing Onions: Cold-Season Crop for Big, Flavorful Bulbs

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Onions are a cold-season crop, easy to grow due to hardiness. Onion sets recommended—plant without frost worry, higher success than seeds/transplants. Grow well on raised beds/rows ≥4 inches high. For indoor growing, see tips for onions from seed.

Planting Onions

• Full sun, no shading from other plants.
• Well-drained, loose, nitrogen-rich soil; compact soil hinders bulbs.
• Till aged manure/fertilizer fall before planting. Heavy feeders need constant nourishment.
• At planting, mix nitrogen fertilizer, side-dress every few weeks until bulbing starts.
• Seeds short-lived. Indoors: fresh seeds yearly, start 6 weeks before transplant.
• Plant as soon as ground workable (late March/April). Temp ≥20°F.
• Sets/transplants: small sets 1 inch deep, 4–5 inches apart, rows 12–18 inches apart.
• Think of onions as leaf crop, not root crop. Don’t bury >1 inch; >⅓ bulb underground restricts growth.
• Rotate crops yearly.
• More regional/soil planting tips.

Care

• Fertilize every few weeks with nitrogen for big bulbs. Stop when bulbing starts (onions push soil away). Don’t push soil back—bulb must emerge.
• Mulch reduces watering need. ~1 inch/week (incl. rain) sufficient. More water = sweeter onions.
• Onions look healthy even bone dry—water in drought.
• Well-drained soil; mulch retains moisture, stifles weeds.
• Cut/pull any flowering stalks—bolting means done.

Pests and Diseases

• Thrips: tiny insects. Knock onion tops on dark paper; tan bodies = thrips. 2–3 insecticidal soap treatments (3 days apart) eliminates.
• Onion Maggots: Cover emerging crop with fine mesh netting, seal with mounded soil. Maggots lay eggs at plant base—netting prevents. Keep mulch away (insects like decay). Harvest completely as season progresses. Most problematic in wet seasons.

Harvest and Storage

• Tops yellow/fall = maturing. Bend/stomp tops to speed ripening.
• Loosen soil for drying. Few days later, turn up, cure on dry ground. Handle gently—bruises cause rot.
• Tops brown = pull.
• Harvest late summer before cool weather. Fall weather spoils mature onions.
• Dry several weeks before storage. Spread on open screen off ground.
• Store 40–50°F in braids or stems broken off.
• Cool, dry for mature bulbs—don’t store with apples/potatoes.

Recommended Varieties

Two categories: Long-day (North), short-day (South).

• ‘Yellow Sweet Spanish’: long-day hybrid, large round, yellow-white.
• ‘Stuttgarter’: short-day sets, early maturity, slightly flat, yellow.

Wit & Wisdom

Onion’s skin very thin,
Mild winter coming in;
Onion’s skin thick and tough,
Coming winter cold and rough.

Recipes

• Grilled French Onion
• Five-Onion Dip
• Onion Sandwich

Cooking Notes

Chopping onions daunting? Four easy steps. Onion skins have health benefits—don’t discard! More kitchen tips.