Frost dates for Thornton, Colorado
In a typical year, Thornton’s last spring frost lands around May 2 and the first fall frost around Oct 11, a growing season of about 162 days. These are odds drawn from 30-year NOAA climate normals, not a promise. USDA zone 6a.
| Odds | Last spring frost | First fall frost |
|---|---|---|
| 10 percent | Apr 18 | Sep 26 |
| 50 percent | May 2 | Oct 11 |
| 90 percent | May 14 | Oct 24 |
A 10 percent year is an early year, a 90 percent year a late one. Frost-sensitive planting usually waits for the 90 percent side of the last-frost band.
Soil in Thornton is typically around 73°F at 4 inches this time of year, estimated from the last two weeks of normal air temperatures.
Plantable now in Thornton
- Chinese cabbage (Bilko)
- Arugula (Astro)
- Mustard greens (Red Giant)
- Tatsoi (Tatsoi)
- Radish (Cherry Belle)
- Beet (Detroit Dark Red)
- Spinach (Space)
- Swiss chard (Bright Lights)
Timing comes from the same temperature engine the app uses, run against Thornton’s normals for today.
Nearby cities
- Westminster, CO (around May 2 to Oct 11)
- Arvada, CO (around May 5 to Oct 5)
- Denver, CO (around Apr 30 to Oct 12)
- Aurora, CO (around May 4 to Oct 8)
- Fort Collins, CO (around May 2 to Oct 7)
Row & Bed is a plant reference built around your garden: your zone, your frost dates, your forecast, and a cited page for every variety in your beds.
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