Cool-season produce

Bulb onion

Allium cepa Cepa Group

Also known as Onion · Yellow onion · Red onion · White onion

Choose short-day or suitable intermediate-day onions for the low desert; long-day northern varieties often fail to bulb properly.

EdibleCool-season crop

Growing spaceVegetable bed

Climate fitUrban core · USDA 9b–10a · Valley suburbs · USDA 9a–9b · Desert outskirts · USDA 8b–9b

Crop familyAmaryllidaceae (allium)

Life cycleAnnual crop

Phoenix planting windowSow short-day varieties October–November; plant sets/transplants December–January.

How to plantDirect sow seed or use short-day transplants/sets; variety day length is decisive.

Plant spacing4–6 in

FrostTolerates light frost once established; cover during a hard freeze.

Time to harvestAbout 4–5 months from sets; 7–8 months from seed in the Maricopa calendar

SuccessionOne main cool-season crop; stagger varieties rather than late sowings.

Special categoriesEDIBLE

Typical harvestBulbs mature in spring as tops fall over.

Right plant, right place

Will Bulb onion grow at your Arizona property?

Choose short-day or suitable intermediate-day onions for the low desert; long-day northern varieties often fail to bulb properly.

Best regional fit: Urban core · USDA 9b–10a, Valley suburbs · USDA 9a–9b, Desert outskirts · USDA 8b–9b.

Light

Full winter sun; give leafy crops afternoon protection during warm fall and spring weather.

Water

Keep the vegetable root zone evenly moist with regular irrigation; adjust to rain, soil, and temperature rather than using a fixed summer schedule.

Planting & stewardship

1
Prepare a fertile, well-drained bed and keep seed or transplants evenly moist through establishment.
2
Thin to the final spacing; crowding reduces harvest quality.
3
Watch for aphids and caterpillars and protect sensitive growth from a hard freeze.
4
Harvest before sustained spring heat causes bolting or poor quality.

Read the growing reference ↗ Planting dates can shift with cultivar, weather, and your yard’s microclimate.