When to plant in Littleton, CO
USDA Zone 6aEverything below — frost dates, hardiness zone, and what to plant when in Littleton, Colorado — is derived from the closest NOAA station with complete climate normals.
Zone 6a means Littleton sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
MARSTON FLTR PLT · 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 Littleton’s own odds, recorded at MARSTON FLTR PLT.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 29 | May 12 | Apr 30 | Sep 17 | Oct 2 | Oct 15 |
| 32°F | May 17 | May 2 | Apr 20 | Sep 27 | Oct 11 | Oct 23 |
| 28°F | May 7 | Apr 23 | Apr 8 | Oct 6 | Oct 21 | Nov 5 |
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 Littleton, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 15 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.
Littleton planting FAQ
When is the last spring frost in Littleton, CO?
Littleton'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 Littleton, CO?
Expect Littleton'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 Littleton in?
Littleton 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 Littleton?
There are roughly 162 frost-free days in Littleton (a moderate growing season), running from the average last frost around May 2 to the first fall frost near October 11.
When should I plant tomatoes in Littleton?
In Littleton, start tomato seeds indoors around March 7–March 21, then transplant seedlings outdoors around May 9 once the danger of frost has passed.
Never miss a window in Littleton
An email when it’s time to start seeds, transplant, and sow — timed to Littleton’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Columbine · 4 km
- Englewood · 7 km
- Highlands Ranch · 7 km
- Ken Caryl · 8 km
- Greenwood Village · 10 km
- Dakota Ridge · 10 km
- Centennial · 13 km
- Cherry Creek · 14 km
Frost dates recorded at MARSTON FLTR PLT, 5 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 Littleton, CO — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00055402. Retrieved from https://blissgarden.com/colorado/littleton.