When to plant in Sterling, CO
USDA Zone 5bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Sterling, Colorado — all computed from Sterling's nearest NOAA weather station.
Zone 5b means Sterling sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
STERLING · 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 Sterling’s own odds, recorded at STERLING.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 24 | May 11 | Apr 30 | Sep 18 | Oct 1 | Oct 11 |
| 32°F | May 12 | Apr 30 | Apr 16 | Sep 28 | Oct 9 | Oct 20 |
| 28°F | May 3 | Apr 18 | Apr 4 | Oct 6 | Oct 18 | 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 Sterling, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 28 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.
Sterling planting FAQ
When is the last spring frost in Sterling, CO?
Sterling's average last spring frost falls near April 30 — 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 Sterling, CO?
The first fall frost in Sterling typically arrives around October 9 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Sterling in?
Sterling 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 Sterling?
There are roughly 162 frost-free days in Sterling (a moderate growing season), running from the average last frost around April 30 to the first fall frost near October 9.
When should I plant tomatoes in Sterling?
In Sterling, start tomato seeds indoors around March 5–March 19, then transplant seedlings outdoors around May 7 once the danger of frost has passed.
Never miss a window in Sterling
An email when it’s time to start seeds, transplant, and sow — timed to Sterling’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Fort Morgan · 65 km
- Evans · 135 km
- Greeley · 135 km
- Severance · 142 km
- Scottsbluff · 144 km
- Windsor · 146 km
- Cheyenne · 146 km
- Johnstown · 150 km
Frost dates recorded at STERLING, 2 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 Sterling, CO — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00057950. Retrieved from https://blissgarden.com/colorado/sterling.