When to plant in Fort Collins, CO
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in Fort Collins, Colorado — is derived from the closest NOAA station with complete climate normals.
In zone 5b, Fort Collins gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
FT COLLINS · 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 Fort Collins’s own odds, recorded at FT COLLINS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 26 | May 12 | May 1 | Sep 15 | Sep 29 | Oct 11 |
| 32°F | May 14 | May 2 | Apr 18 | Sep 24 | Oct 7 | Oct 20 |
| 28°F | May 5 | Apr 20 | Apr 5 | Oct 2 | Oct 17 | Oct 28 |
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 Fort Collins, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 13 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.
Fort Collins planting FAQ
When is the last spring frost in Fort Collins, CO?
Plan for the last spring frost in Fort Collins around May 2 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Fort Collins, CO?
Expect Fort Collins's first fall frost near October 7 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Fort Collins in?
Fort Collins 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 Fort Collins?
Fort Collins has about 158 frost-free days — a moderate growing season — between the average last spring frost (May 2) and first fall frost (October 7).
When should I plant tomatoes in Fort Collins?
For Fort Collins, sow tomatoes indoors about March 7–March 21 and move the seedlings out around May 9, after the last spring frost.
Never miss a window in Fort Collins
An email when it’s time to start seeds, transplant, and sow — timed to Fort Collins’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at FT COLLINS, 4 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 Fort Collins, CO — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00053005. Retrieved from https://blissgarden.com/colorado/fort-collins.