Steamboat Springs, CO planting zone & frost dates
Steamboat Springs is in USDA hardiness zone 4b. The last spring frost usually comes around June 9 and the first fall frost around September 12, for a growing season of about 93 days.
Planting calendar for Steamboat Springs
Dates are counted from the average last spring frost (June 9) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Apr 14 – Apr 28 Transplant outdoors: Jun 16 – Jun 23 |
| Peppers | Start seeds indoors: Mar 31 – Apr 14 Transplant outdoors: Jun 23 – Jun 30 |
| Eggplant | Start seeds indoors: Mar 31 – Apr 14 Transplant outdoors: Jun 23 – Jun 30 |
| Broccoli | Start seeds indoors: Mar 31 – Apr 14 Transplant outdoors: May 12 – May 26 |
| Cabbage | Start seeds indoors: Mar 31 – Apr 14 Transplant outdoors: May 12 – May 26 |
| Onions (sets) | Plant outdoors: May 12 – May 26 |
| Peas | Sow outdoors: Apr 28 – May 12 |
| Spinach | Sow outdoors: Apr 28 – May 12 |
| Lettuce | Sow outdoors: May 12 – May 26 |
| Carrots | Sow outdoors: May 12 – May 26 |
| Potatoes | Plant outdoors: May 12 – May 26 |
| Beans | Sow outdoors: Jun 16 – Jun 23 |
| Sweet corn | Sow outdoors: Jun 16 – Jun 23 |
| Cucumbers | Sow outdoors: Jun 16 – Jun 23 |
| Squash & zucchini | Sow outdoors: Jun 16 – Jun 23 |
| Basil | Start seeds indoors: Apr 28 – May 12 Transplant outdoors: Jun 16 – Jun 23 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Jul 18 (8 weeks before the average first fall frost on Sep 12).
Useful for zone 4b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | May 25 | Jun 9 | Jun 24 |
| First 32°F frost in fall is before | Sep 24 | Sep 12 | Aug 31 |
How to read it: in spring there is a 10% chance of a frost after June 24, so that is a safe date for tender plants. In fall there is a 10% chance of frost before August 31. A hard freeze (28°F) usually ends around May 20.
Hardiness zone by ZIP code in Steamboat Springs
- 80477 zone 4b
- 80487 zone 5b
- 80488 zone 4b
Nearby cities
- Edwards zone 5b, last frost Jun 6
- Boulder zone 6a, last frost May 6
- Superior zone 6a, last frost May 6
- Fort Collins zone 5b, last frost May 2
- Longmont zone 5b, last frost May 7
- Loveland zone 5b, last frost May 10
- Golden zone 6a, last frost May 3
- Louisville zone 6a, last frost May 6
Questions
What growing zone is Steamboat Springs, CO?
Steamboat Springs is in USDA Plant Hardiness Zone 4b (average extreme winter low -25°F to -20°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 5b.
When is the last frost in Steamboat Springs?
The average last spring frost (32°F) in Steamboat Springs is June 9. There is still a 10% chance of frost until June 24.
When can I plant tomatoes in Steamboat Springs?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Jun 16 – Jun 23. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Steamboat Springs, CO (USC00057936), 0.8 km (0.5 mi) from the city center, elevation 2093 m, based on 23 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.