When to plant in Firestone, CO
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in Firestone, Colorado — is derived from the closest NOAA station with complete climate normals.
In zone 5b, Firestone gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average first fall frost in Firestone is now 8 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
LONGMONT 2 ESE · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Firestone’s own odds, recorded at LONGMONT 2 ESE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 2 | May 18 | May 5 | Sep 14 | Sep 28 | Oct 8 |
| 32°F | May 22 | May 7 | Apr 24 | Sep 23 | Oct 5 | Oct 16 |
| 28°F | May 12 | Apr 28 | Apr 11 | Sep 30 | Oct 12 | Oct 25 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Firestone, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 29 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Firestone planting FAQ
When is the last spring frost in Firestone, CO?
On average, the last spring frost in Firestone is around May 7 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Firestone, CO?
The first fall frost in Firestone typically arrives around October 5 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Firestone in?
Firestone is in USDA hardiness zone 5b. In zone 5b, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Firestone?
Firestone has about 151 frost-free days — a moderate growing season — between the average last spring frost (May 7) and first fall frost (October 5).
When should I plant tomatoes in Firestone?
For Firestone, sow tomatoes indoors about March 12–March 26 and move the seedlings out around May 14, after the last spring frost.
Never miss a window in Firestone
An email when it’s time to start seeds, transplant, and sow — timed to Firestone’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at LONGMONT 2 ESE, 11 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Firestone, CO — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00055116. Retrieved from https://blissgarden.com/colorado/firestone.