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Can You Grow Onion in Colorado?

US · USDA Zone 5b · zones 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b

Grows well here

Onions grow well here — plant sets or transplants in early spring for a summer harvest.

Plant zones

2a–9b

Colorado last frost

early April

Colorado first frost

late October

Days to harvest

90–120 days

When to plant Onions in Colorado

Start indoors

Feb 9

Transplant

Apr 7

Harvest

Jul 6 – Aug 5

Dates are approximate, based on Colorado's average frost dates. Your exact yard may vary by microclimate.

About Onion

Onions are a staple crop that stores well and can be grown as sets transplants or from seed.

Growing from sets is easiest for beginners. Plant in early spring — onions are frost-tolerant. Day-length sensitive — choose short-day long-day or day-neutral varieties based on your latitude.

Full onion growing guide →

Gardening in Colorado

Colorado has a semi-arid mountain climate with intense sunshine and low humidity. Front Range cities like Denver are Zone 5-6; higher elevations are Zones 3-4.

See what grows well in Colorado →

Frequently asked questions

Can you grow Onion in Colorado?

Onions grow well here — plant sets or transplants in early spring for a summer harvest.

What zone is Colorado?

Colorado spans USDA Zone 5b (3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b).

When do you plant Onions in Colorado?

Plant Onions around early April (start indoors Feb 9), harvest Jul 6 – Aug 5.