When to plant in Superior, CO
USDA Zone 6aSuperior, 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 6a, Superior gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
BOULDER · 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 Superior’s own odds, recorded at BOULDER.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 2 | May 17 | May 5 | Sep 13 | Sep 28 | Oct 10 |
| 32°F | May 18 | May 6 | Apr 24 | Sep 21 | Oct 5 | Oct 18 |
| 28°F | May 10 | Apr 27 | Apr 10 | Sep 30 | Oct 15 | Oct 30 |
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 Superior, 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.
Superior planting FAQ
When is the last spring frost in Superior, CO?
Plan for the last spring frost in Superior around May 6 (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 Superior, CO?
In Superior, the first 32°F freeze of fall lands around October 5 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Superior in?
Superior is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Superior?
Superior has about 152 frost-free days — a moderate growing season — between the average last spring frost (May 6) and first fall frost (October 5).
When should I plant tomatoes in Superior?
For Superior, sow tomatoes indoors about March 11–March 25 and move the seedlings out around May 13, after the last spring frost.
Never miss a window in Superior
An email when it’s time to start seeds, transplant, and sow — timed to Superior’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Louisville · 4 km
- Lafayette · 9 km
- Broomfield · 10 km
- Westminster · 10 km
- Arvada · 11 km
- Boulder · 13 km
- Federal Heights · 14 km
- Gunbarrel · 15 km
Frost dates recorded at BOULDER, 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 Superior, CO — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00050848. Retrieved from https://blissgarden.com/colorado/superior.