When to plant in Brighton, CO
USDA Zone 5bBrighton, Colorado frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
In zone 5b, Brighton gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
BRIGHTON 3 SE · 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 Brighton’s own odds, recorded at BRIGHTON 3 SE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 27 | May 13 | May 3 | Sep 17 | Sep 30 | Oct 10 |
| 32°F | May 16 | May 3 | Apr 22 | Sep 26 | Oct 7 | Oct 19 |
| 28°F | May 7 | Apr 23 | Apr 8 | Oct 4 | Oct 16 | Oct 29 |
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 Brighton, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 20 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.
Brighton planting FAQ
When is the last spring frost in Brighton, CO?
Brighton's average last spring frost falls near May 3 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Brighton, CO?
In Brighton, the first 32°F freeze of fall lands around October 7 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Brighton in?
Brighton 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 Brighton?
Brighton has about 157 frost-free days — a moderate growing season — between the average last spring frost (May 3) and first fall frost (October 7).
When should I plant tomatoes in Brighton?
For Brighton, sow tomatoes indoors about March 8–March 22 and move the seedlings out around May 10, after the last spring frost.
Never miss a window in Brighton
An email when it’s time to start seeds, transplant, and sow — timed to Brighton’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Commerce City · 9 km
- Thornton · 14 km
- Northglenn · 17 km
- Welby · 20 km
- Frederick · 22 km
- Broomfield · 22 km
- Federal Heights · 22 km
- Erie · 22 km
Frost dates recorded at BRIGHTON 3 SE, 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 Brighton, CO — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00050950. Retrieved from https://blissgarden.com/colorado/brighton.