Onion
Allium cepa
Onions bulb in response to day length, not maturity — a long-day onion planted in Florida will never bulb because the sun never gets high enough, no matter how much you fertilize or water.
How to care for onion
Match the variety to your latitude — short-day onions (south of 35°N), intermediate (35-38°N), long-day (north of 38°N). Wrong day-length = small bulbs. Stop watering when tops yellow and fall; cure for 2 weeks before storing.
Garden uses & design ideas
Best garden use
Give it a practical bed with easy reach, steady water, and companion flowers nearby to support pollinators and pest balance.
Pair it with
Tomato, Carrots, Beet make easy companion choices because they share similar light, water, or visual texture needs.
Layout tip
Match it with full sun exposure, place it in a moderate-water bed where soil can stay evenly damp but not soggy, and check USDA zones 2-10 (cool-season annual or biennial) before planting. Use the garden planner to test spacing around its mature size: 12-24 in tall (foliage); bulbs 1-4 in across.
Gardener note — Double-check local invasive, edible, and toxicity guidance with your county extension office before planting around pets, children, or natural areas.
Companion plants
Onion grows well alongside these — similar light, water, and texture needs.
Common pests & problems
Where it grows best
Native to Central Asia; thrives in USDA hardiness zones 2-10 (cool-season annual or biennial).
Frequently asked about onion
What USDA zones does Onion grow in?+
Onion is hardy in USDA zones 2-10 (cool-season annual or biennial). Outside these zones, it can usually be grown indoors or as a seasonal annual.
How much sun does Onion need?+
Onion prefers full sun. Place it where it gets that light most of the day for best growth and vigor.
How often should I water Onion?+
Onion has moderate water needs. Keep soil consistently moist but not soggy. Match the variety to your latitude — short-day onions (south of 35°N), intermediate (35-38°N), long-day (north of 38°N). Wrong day-length = small bulbs. Stop watering when tops yellow and fall; cure for 2 weeks before storing.
How big does Onion get?+
Onion reaches a mature size of 12-24 in tall (foliage); bulbs 1-4 in across. Growth rate is moderate, so plan spacing accordingly when planting.
What plants grow well with Onion?+
Onion pairs well with Tomato, Carrots, Beet, Cabbage, Strawberry. These companions share similar care requirements and don't compete aggressively for resources.
What pests affect Onion?+
Common Onion problems include onion maggot; thrips; downy mildew. Catching early signs in routine inspection prevents most damage.
Design a garden with onion in minutes
Drag plants into a 3D space, walk through it, or upload a photo and let AI redesign it. Test spacing around its mature size before you plant.
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