When to plant in Welby, CO
USDA Zone 6aWelby, 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, Welby gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
NORTHGLENN · 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 Welby’s own odds, recorded at NORTHGLENN.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 26 | May 12 | Apr 30 | Sep 18 | Oct 1 | Oct 14 |
| 32°F | May 14 | May 2 | Apr 18 | Sep 26 | Oct 11 | Oct 24 |
| 28°F | May 5 | Apr 20 | Apr 4 | Oct 7 | Oct 21 | Nov 4 |
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 Welby, 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.
Welby planting FAQ
When is the last spring frost in Welby, CO?
Welby's average last spring frost falls near May 2 — 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 Welby, CO?
Expect Welby's first fall frost near October 11 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Welby in?
Welby 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 Welby?
Welby has about 162 frost-free days — a moderate growing season — between the average last spring frost (May 2) and first fall frost (October 11).
When should I plant tomatoes in Welby?
For Welby, 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 Welby
An email when it’s time to start seeds, transplant, and sow — timed to Welby’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Sherrelwood · 3 km
- Federal Heights · 5 km
- Berkley · 7 km
- Northglenn · 8 km
- Thornton · 9 km
- Westminster · 9 km
- Denver · 11 km
- Wheat Ridge · 14 km
Frost dates recorded at NORTHGLENN, 8 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 Welby, CO — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00055984. Retrieved from https://blissgarden.com/colorado/welby.