Frost Dates & Planting Calendar for Gillette, WY
Plan your garden around Gillette, WY's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.
Last Spring Frost
May 15
Safe May 27
Typical May 15
Risky May 1
First Fall Frost
October 1
Safe Sep 15
Typical Oct 1
Risky Oct 14
Growing Season
136 days
Typical last frost to typical first frost.
USDA Hardiness Zone
Zone 5a
A classic four-season climate with cold winters and a solid summer growing season.
Data: NOAA station GILLETTE 4SE, WY US, 5 km away.
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days until the typical last spring frost
Monthly Temperatures
Avg. high
Avg. temp
Avg. low
Planting Calendar
| Crop | Start indoors | Direct sow | Transplant | Fall planting | Maturity | Notes |
|---|---|---|---|---|---|---|
| Tomato | Mar 20 – Apr 3 | — | May 22 – May 29 | — | 60–85 days | Start indoors 6-8 weeks before last frost; transplant out 1-2 weeks after last frost once soil has warmed. |
| Pepper | Mar 6 – Mar 20 | — | May 22 – Jun 5 | — | 60–90 days | Slow to germinate; start indoors 8-10 weeks before last frost. Transplant only once nights stay above 55F, 1-3 weeks after last frost. |
| Eggplant | Mar 6 – Mar 20 | — | May 29 – Jun 5 | — | 65–85 days | Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant. |
| Cucumber | Apr 17 – Apr 24 | May 22 – May 29 | May 22 – May 29 | — | 50–65 days | Can be started indoors 3-4 weeks before transplanting, or direct-sown 1-2 weeks after last frost once soil is warm. |
| Zucchini | Apr 24 – May 1 | May 22 – Jun 5 | May 22 – May 29 | — | 45–55 days | Fast-growing squash; direct sow 1-3 weeks after last frost, or start indoors 2-3 weeks early for a head start. |
| Winter Squash | Apr 17 – Apr 24 | May 22 – Jun 5 | May 22 – May 29 | — | 80–110 days | Long season; direct sow after soil warms, or start indoors 3-4 weeks before last frost in short-season climates. |
| Pumpkin | — | May 22 – Jun 5 | — | — | 90–120 days | Direct sow 1-3 weeks after last frost; back-time from your first fall frost so the 90-120 day maturity window lands before it. |
| Watermelon | Apr 17 – Apr 24 | — | May 29 – Jun 5 | — | 70–90 days | Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost. |
| Cantaloupe | Apr 17 – Apr 24 | — | May 29 – Jun 5 | — | 70–90 days | Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting. |
| Corn | — | May 15 – May 29 | — | — | 60–100 days | Direct sow at last frost to 2 weeks after, once soil reaches 60F; does not transplant well. Succession sow every 2 weeks. |
| Green Bean | — | May 15 – May 29 | — | — | 50–65 days | Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush. |
| Pea | — | Apr 3 – Apr 17 | — | — | 55–70 days | Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Lettuce | — | Apr 17 – May 1 | — | Aug 6 – Aug 20 | 45–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts. |
| Spinach | — | Apr 3 – Apr 17 | — | Aug 6 – Aug 20 | 40–50 days | Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Kale | — | Apr 17 – May 1 | — | Jul 23 – Aug 6 | 50–65 days | Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants. |
| Arugula | — | Apr 17 – May 1 | — | Aug 20 – Aug 27 | 30–40 days | Fast-growing, cold-tolerant green; direct sow 2-4 weeks before last frost, succession sow every 2-3 weeks. |
| Swiss Chard | — | Apr 24 – May 8 | — | — | 50–60 days | Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too. |
| Broccoli | Mar 27 – Apr 10 | — | Apr 24 – May 1 | Jul 30 – Aug 6 | 55–80 days | Start indoors 5-7 weeks before last frost; transplant out 2-3 weeks before last frost (hardens off to light frost). |
| Cauliflower | Mar 27 – Apr 10 | — | May 1 – May 8 | Jul 23 – Jul 30 | 55–85 days | Fussier than broccoli about temperature swings; start indoors 5-7 weeks before last frost, transplant 1-2 weeks before last frost. |
| Cabbage | Mar 27 – Apr 10 | — | Apr 17 – May 1 | Jul 23 – Aug 6 | 60–100 days | Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost. |
| Brussels Sprouts | Mar 27 – Apr 10 | — | Apr 24 – May 8 | — | 90–110 days | Long-season crop best timed to mature after a light fall frost for sweetest flavor; start indoors 5-7 weeks before last frost. |
| Carrot | — | Apr 17 – May 1 | — | Jul 9 – Jul 23 | 60–80 days | Direct sow only (does not transplant); sow 2-4 weeks before last frost, as soon as soil can be worked. |
| Beet | — | Apr 17 – May 1 | — | Jul 23 – Aug 6 | 50–65 days | Direct sow 2-4 weeks before last frost; tolerates light frost. |
| Radish | — | Apr 10 – Apr 24 | — | Aug 20 – Sep 3 | 22–30 days | Very fast and cold-hardy; direct sow 3-5 weeks before last frost, as soon as soil can be worked. |
| Turnip | — | Apr 17 – May 1 | — | Jul 23 – Aug 6 | 40–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. |
| Onion | Mar 6 – Mar 20 | — | Apr 17 – May 1 | — | 90–120 days | Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings. |
| Garlic | — | — | — | Sep 3 – Sep 17 | 240–270 days | Fall-planted crop only; not planted in spring in most climates. |
| Potato | — | Apr 17 – May 1 | — | — | 70–120 days | Plant seed potatoes 2-4 weeks before last frost, as soon as soil can be worked and is above 45F; light frost on emerging foliage is usually tolerated. |
| Sweet Potato | — | — | May 29 – Jun 12 | — | 90–120 days | Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive. |
| Asparagus | — | — | Apr 17 – May 1 | — | 730–1095 days | Perennial; plant crowns 2-4 weeks before last frost as soon as soil can be worked. Takes 2-3 years to full production. |
| Crop | Start indoors | Direct sow | Transplant | Fall planting | Maturity | Notes |
|---|---|---|---|---|---|---|
| Basil | Apr 3 – Apr 10 | — | May 22 – May 29 | — | 50–70 days | Very frost/cold sensitive; start indoors 5-6 weeks before last frost, transplant only after all danger of frost (1-2 weeks after) and nights stay warm. |
| Cilantro | — | Apr 24 – May 8 | — | Aug 6 – Aug 20 | 45–70 days | Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring. |
| Parsley | Mar 20 – Apr 3 | — | May 1 – May 8 | — | 70–90 days | Slow to germinate; start indoors 6-8 weeks before last frost, transplant 1-2 weeks before last frost (biennial, cold-tolerant). |
| Dill | — | Apr 24 – May 8 | — | — | 40–60 days | Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer. |
| Oregano | Mar 20 – Apr 3 | — | May 15 – May 22 | — | 80–90 days | Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date. |
| Thyme | Mar 20 – Apr 3 | — | May 15 – May 22 | — | 85–95 days | Perennial herb, slow from seed; start indoors 6-8 weeks before last frost, transplant around/after last frost. |
| Crop | Start indoors | Direct sow | Transplant | Fall planting | Maturity | Notes |
|---|---|---|---|---|---|---|
| Sunflower | — | May 22 – Jun 5 | — | — | 70–100 days | Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting. |
| Zinnia | Apr 17 – Apr 24 | May 22 – Jun 5 | May 22 – May 29 | — | 60–70 days | Frost-tender; direct sow 1-3 weeks after last frost, or start indoors 3-4 weeks early for earlier blooms. |
| Marigold | Apr 3 – Apr 17 | — | May 22 – May 29 | — | 45–60 days | Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed. |
| Cosmos | Apr 17 – Apr 24 | May 22 – Jun 5 | May 22 – May 29 | — | 60–90 days | Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early. |
| Nasturtium | — | May 22 – Jun 5 | — | — | 50–65 days | Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed. |
| Dahlia | — | — | May 22 – Jun 5 | — | 90–120 days | Plant tubers 1-3 weeks after last frost once soil is warm (60F+); very frost-sensitive. |
Date ranges are estimates based on university extension guidelines and this city's NOAA frost normals — not a guarantee. Scroll to see all columns on narrow screens.
Frequently Asked Questions
When is the last frost in Gillette, WY?
Based on 1991–2020 NOAA climate normals for the GILLETTE 4SE, WY US station, the last spring frost in Gillette typically falls around May 15. A cautious gardener might wait until May 27 (only a 10% chance of a later frost), while May 1 marks an earlier, higher-risk planting date.
When is the first frost in Gillette, WY in fall?
The first fall frost in Gillette typically arrives around October 1. To stay safe, assume frost could start as early as September 15; in milder years it can hold off until October 14.
How long is the growing season in Gillette, WY?
Gillette's average frost-free growing season is about 136 days, running from the typical last spring frost (May 15) to the typical first fall frost (October 1).
What USDA hardiness zone is Gillette, WY in?
Gillette, WY is in USDA plant hardiness zone 5a, per the USDA's 2023 Plant Hardiness Zone Map. A classic four-season climate with cold winters and a solid summer growing season.