USDA Zone 6a — Garden & Frost Dates for Denver, CO (80221)
This is the local garden report for ZIP code 80221 (Denver, CO). It pairs the official USDA 2023 hardiness zone with NOAA-based frost dates so you can plan seeds, transplants, and fall crops with real numbers for your neighborhood.
What does zone 6a mean for Denver?
Zone 6a is the USDA Plant Hardiness Zone for ZIP 80221, based on the 30-year (1991-2020) average annual extreme minimum winter temperature. Perennial plants labeled for zone 6a or lower should survive a typical winter here. The last spring frost averages 04-28 and the first fall frost averages 10-08, giving roughly 163 frost-free growing days — the window that most vegetables need to go from seed to harvest.
Start your Denver planting calendar
This calendar is pre-loaded with the exact frost dates for ZIP 80221 (Denver, CO) — more precise than a state-wide average. Pick a crop and print the plan.
In this ZIP (typical zone 3–7), last frost ≈ Apr 28, first frost ≈ Oct 8 (163-day season), your Tomato plan:
Month-by-month (this ZIP, 2026)
| Month | Action |
|---|---|
| Jan | — |
| Feb | — |
| Mar | Start indoors |
| Apr | — |
| May | Sow · Transplant |
| Jun | — |
| Jul | Harvest |
| Aug | — |
| Sep | — |
| Oct | — |
| Nov | — |
| Dec | — |
Start indoors 6 weeks before last frost; transplant after soil warms. Zones 3–13 suitable. Dates are typical; confirm with your county extension and watch the 10-day forecast.
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