Cheyenne, Wyoming: planting zone & frost dates
Cheyenne is in USDA plant hardiness zone 5b, where the average coldest winter night reaches -15 to -10°F (-26.1 to -23.3°C). The typical last spring frost is around May 20 and the first fall frost around Sep 26.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 28 | Sep 17 |
| Typical planning date (30% risk) | May 20 | Sep 26 |
| Median (50%) | May 14 | Oct 1 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station CHEYENNE WFO, WY (USC00481676), 1.8 mi (2.9 km) from the city center and 79 ft higher than the city center (+24 m). Record used for the 1991–2020 normals: 18 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Cheyenne
All 3 ZIP codes covering Cheyenne are in zone 5b.
Vegetable planting calendar for Cheyenne
Dates are counted from the 30%-risk frost dates above (last frost May 20, first frost Sep 26). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 25 – Apr 8 | May 27 – Jun 10 | — | — |
| Pepper | Mar 11 – Mar 25 | Jun 3 – Jun 17 | — | — |
| Lettuce | Apr 8 – Apr 22 | May 6 – May 27 | Apr 22 – Jun 3 | Jul 18 – Aug 15 |
| Green Beans | — | — | May 27 – Jul 1 | Jul 4 – Jul 18 |
| Sweet Corn | — | — | May 27 – Jun 24 | — |
| Zucchini & Summer Squash | Apr 22 – Apr 29 | May 27 – Jun 10 | May 27 – Jun 17 | Jul 4 – Jul 18 |
| Cucumber | Apr 22 – Apr 29 | Jun 3 – Jun 10 | May 27 – Jun 17 | Jul 4 – Jul 18 |
| Carrot | — | — | Apr 29 – Jun 3 | Jul 4 – Jul 18 |
| Onion | Feb 25 – Mar 11 | Apr 22 – May 6 | — | — |
| Potato | — | Apr 22 – May 13 | — | — |
| Basil | Apr 8 – Apr 22 | Jun 3 – Jun 17 | Jun 3 – Jun 24 | — |
| Spinach | — | — | Apr 8 – May 6 | Aug 1 – Aug 29 |
| Kale | Mar 25 – Apr 8 | Apr 22 – May 13 | Apr 22 – May 13 | Jul 18 – Aug 15 |
| Broccoli | Mar 25 – Apr 8 | May 6 – May 27 | — | Jul 4 – Jul 18 |
| Peas | — | — | Apr 8 – Apr 29 | Jul 18 – Aug 1 |
| Eggplant | Mar 11 – Mar 25 | Jun 3 – Jun 17 | — | — |
| Cabbage | Mar 25 – Apr 8 | Apr 22 – May 6 | — | Jul 4 – Jul 18 |
| Radish | — | — | Apr 15 – Jun 3 | Aug 15 – Sep 12 |
| Strawberry | — | Apr 22 – May 13 | — | — |
| Beets | — | — | Apr 29 – Jun 10 | Jul 18 – Aug 1 |
Nearby cities in Wyoming
- Casper — zone 5a, last frost May 16, first frost Sep 23
More: all Wyoming cities · other zone 5b cities: Madison, WI, Des Moines, IA, Aurora, IL, Fort Collins, CO, Naperville, IL, Rockford, IL, Elgin, IL, Greeley, CO
Cheyenne gardening questions
When is the last frost in Cheyenne, WY?
Plan around May 20. At NOAA's Cheyenne Wfo, WY station, 1.8 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by May 14, and after May 28 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around May 3. The last frost is fairly predictable here: only 25 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Cheyenne, WY?
Start seeds indoors Mar 25 – Apr 8 and set transplants outside May 27 – Jun 10, once nights stay above 50°F and the soil is near 60°F. That leaves 129 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Cheyenne?
About 139 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 119 days, and in 1 year in 10 it runs 155 days or more. In fall there is a 10% chance of frost by Sep 17 and a 30% chance by Sep 26.
When should I plant a fall garden in Cheyenne?
Count back from the first fall frost (Sep 26): transplant broccoli Jul 4 – Jul 18; sow kale Jul 18 – Aug 15; sow lettuce Jul 18 – Aug 15; sow radishes Aug 15 – Sep 12. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 10. How the math works: succession and fall planting.
Did Cheyenne's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Cheyenne is zone 5b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
How does Cheyenne compare with Fort Collins, CO?
Both are in zone 5b. The typical last spring frost in Cheyenne (May 20) comes about 13 days later than in Fort Collins, CO (May 7), 43 miles away, and the first fall frost is Sep 26 versus Oct 2. Cheyenne sits about 1,049 ft higher, which explains part of the gap. The two cities use different NOAA stations.