Frost Dates & Planting Calendar for Butte, MT
Plan your garden around Butte, MT's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.
Last Spring Frost
June 13
Safe Jul 1
Typical Jun 13
Risky May 27
First Fall Frost
September 5
Safe Aug 24
Typical Sep 5
Risky Sep 19
Growing Season
83 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 BUTTE BERT MOONEY AP, MT US, 5.1 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 | Apr 18 – May 2 | — | Jun 20 – Jun 27 | — | 60–85 days | Start indoors 6-8 weeks before last frost; transplant out 1-2 weeks after last frost once soil has warmed. |
| Pepper | Apr 4 – Apr 18 | — | Jun 20 – Jul 4 | — | 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 | Apr 4 – Apr 18 | — | Jun 27 – Jul 4 | — | 65–85 days | Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant. |
| Cucumber | May 16 – May 23 | Jun 20 – Jun 27 | Jun 20 – Jun 27 | — | 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 | May 23 – May 30 | Jun 20 – Jul 4 | Jun 20 – Jun 27 | — | 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 | May 16 – May 23 | Jun 20 – Jul 4 | Jun 20 – Jun 27 | — | 80–110 days | Long season; direct sow after soil warms, or start indoors 3-4 weeks before last frost in short-season climates. |
| Pumpkin | — | Jun 20 – Jul 4 | — | — | 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 | May 16 – May 23 | — | Jun 27 – Jul 4 | — | 70–90 days | Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost. |
| Cantaloupe | May 16 – May 23 | — | Jun 27 – Jul 4 | — | 70–90 days | Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting. |
| Corn | — | Jun 13 – Jun 27 | — | — | 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 | — | Jun 13 – Jun 27 | — | — | 50–65 days | Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush. |
| Pea | — | May 2 – May 16 | — | — | 55–70 days | Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Lettuce | — | May 16 – May 30 | — | Jul 11 – Jul 25 | 45–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts. |
| Spinach | — | May 2 – May 16 | — | Jul 11 – Jul 25 | 40–50 days | Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Kale | — | May 16 – May 30 | — | Jun 27 – Jul 11 | 50–65 days | Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants. |
| Arugula | — | May 16 – May 30 | — | Jul 25 – Aug 1 | 30–40 days | Fast-growing, cold-tolerant green; direct sow 2-4 weeks before last frost, succession sow every 2-3 weeks. |
| Swiss Chard | — | May 23 – Jun 6 | — | — | 50–60 days | Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too. |
| Broccoli | Apr 25 – May 9 | — | May 23 – May 30 | Jul 4 – Jul 11 | 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 | Apr 25 – May 9 | — | May 30 – Jun 6 | Jun 27 – Jul 4 | 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 | Apr 25 – May 9 | — | May 16 – May 30 | Jun 27 – Jul 11 | 60–100 days | Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost. |
| Brussels Sprouts | Apr 25 – May 9 | — | May 23 – Jun 6 | — | 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 | — | May 16 – May 30 | — | Jun 13 – Jun 27 | 60–80 days | Direct sow only (does not transplant); sow 2-4 weeks before last frost, as soon as soil can be worked. |
| Beet | — | May 16 – May 30 | — | Jun 27 – Jul 11 | 50–65 days | Direct sow 2-4 weeks before last frost; tolerates light frost. |
| Radish | — | May 9 – May 23 | — | Jul 25 – Aug 8 | 22–30 days | Very fast and cold-hardy; direct sow 3-5 weeks before last frost, as soon as soil can be worked. |
| Turnip | — | May 16 – May 30 | — | Jun 27 – Jul 11 | 40–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. |
| Onion | Apr 4 – Apr 18 | — | May 16 – May 30 | — | 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 | — | — | — | Aug 8 – Aug 22 | 240–270 days | Fall-planted crop only; not planted in spring in most climates. |
| Potato | — | May 16 – May 30 | — | — | 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 | — | — | Jun 27 – Jul 11 | — | 90–120 days | Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive. |
| Asparagus | — | — | May 16 – May 30 | — | 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 | May 2 – May 9 | — | Jun 20 – Jun 27 | — | 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 | — | May 23 – Jun 6 | — | Jul 11 – Jul 25 | 45–70 days | Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring. |
| Parsley | Apr 18 – May 2 | — | May 30 – Jun 6 | — | 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 | — | May 23 – Jun 6 | — | — | 40–60 days | Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer. |
| Oregano | Apr 18 – May 2 | — | Jun 13 – Jun 20 | — | 80–90 days | Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date. |
| Thyme | Apr 18 – May 2 | — | Jun 13 – Jun 20 | — | 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 | — | Jun 20 – Jul 4 | — | — | 70–100 days | Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting. |
| Zinnia | May 16 – May 23 | Jun 20 – Jul 4 | Jun 20 – Jun 27 | — | 60–70 days | Frost-tender; direct sow 1-3 weeks after last frost, or start indoors 3-4 weeks early for earlier blooms. |
| Marigold | May 2 – May 16 | — | Jun 20 – Jun 27 | — | 45–60 days | Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed. |
| Cosmos | May 16 – May 23 | Jun 20 – Jul 4 | Jun 20 – Jun 27 | — | 60–90 days | Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early. |
| Nasturtium | — | Jun 20 – Jul 4 | — | — | 50–65 days | Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed. |
| Dahlia | — | — | Jun 20 – Jul 4 | — | 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 Butte, MT?
Based on 1991–2020 NOAA climate normals for the BUTTE BERT MOONEY AP, MT US station, the last spring frost in Butte typically falls around June 13. A cautious gardener might wait until July 1 (only a 10% chance of a later frost), while May 27 marks an earlier, higher-risk planting date.
When is the first frost in Butte, MT in fall?
The first fall frost in Butte typically arrives around September 5. To stay safe, assume frost could start as early as August 24; in milder years it can hold off until September 19.
How long is the growing season in Butte, MT?
Butte's average frost-free growing season is about 83 days, running from the typical last spring frost (June 13) to the typical first fall frost (September 5).
What USDA hardiness zone is Butte, MT in?
Butte, MT 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.