Gillette, WY planting zone & frost dates
Gillette is in USDA hardiness zone 5a. The last spring frost usually comes around May 15 and the first fall frost around October 1, for a growing season of about 136 days.
Planting calendar for Gillette
Dates are counted from the average last spring frost (May 15) 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: Mar 20 – Apr 3 Transplant outdoors: May 22 – May 29 |
| Peppers | Start seeds indoors: Mar 6 – Mar 20 Transplant outdoors: May 29 – Jun 5 |
| Eggplant | Start seeds indoors: Mar 6 – Mar 20 Transplant outdoors: May 29 – Jun 5 |
| Broccoli | Start seeds indoors: Mar 6 – Mar 20 Transplant outdoors: Apr 17 – May 1 |
| Cabbage | Start seeds indoors: Mar 6 – Mar 20 Transplant outdoors: Apr 17 – May 1 |
| Onions (sets) | Plant outdoors: Apr 17 – May 1 |
| Peas | Sow outdoors: Apr 3 – Apr 17 |
| Spinach | Sow outdoors: Apr 3 – Apr 17 |
| Lettuce | Sow outdoors: Apr 17 – May 1 |
| Carrots | Sow outdoors: Apr 17 – May 1 |
| Potatoes | Plant outdoors: Apr 17 – May 1 |
| Beans | Sow outdoors: May 22 – May 29 |
| Sweet corn | Sow outdoors: May 22 – May 29 |
| Cucumbers | Sow outdoors: May 22 – May 29 |
| Squash & zucchini | Sow outdoors: May 22 – May 29 |
| Basil | Start seeds indoors: Apr 3 – Apr 17 Transplant outdoors: May 22 – May 29 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 6 (8 weeks before the average first fall frost on Oct 1).
Useful for zone 5a 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 1 | May 15 | May 27 |
| First 32°F frost in fall is before | Oct 14 | Oct 1 | Sep 15 |
How to read it: in spring there is a 10% chance of a frost after May 27, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 15. A hard freeze (28°F) usually ends around May 2.
Hardiness zone by ZIP code in Gillette
- 82716 zone 5a
- 82717 zone 5a
- 82718 zone 5a
Nearby cities
Questions
What growing zone is Gillette, WY?
Gillette is in USDA Plant Hardiness Zone 5a (average extreme winter low -20°F to -15°F), according to the USDA 2023 map.
When is the last frost in Gillette?
The average last spring frost (32°F) in Gillette is May 15. There is still a 10% chance of frost until May 27.
When can I plant tomatoes in Gillette?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 22 – May 29. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Gillette 4Se, WY (USC00483855), 5.0 km (3.1 mi) from the city center, elevation 1414 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.