Frost Dates & Planting Calendar for Bozeman, MT
Plan your garden around Bozeman, MT's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.
Last Spring Frost
May 26
Safe Jun 14
Typical May 26
Risky May 9
First Fall Frost
September 22
Safe Sep 5
Typical Sep 22
Risky Oct 5
Growing Season
116 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 BOZEMAN MONTANA STATE UNIV, MT US, 2 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 31 – Apr 14 | — | Jun 2 – Jun 9 | — | 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 17 – Mar 31 | — | Jun 2 – Jun 16 | — | 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 17 – Mar 31 | — | Jun 9 – Jun 16 | — | 65–85 days | Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant. |
| Cucumber | Apr 28 – May 5 | Jun 2 – Jun 9 | Jun 2 – Jun 9 | — | 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 5 – May 12 | Jun 2 – Jun 16 | Jun 2 – Jun 9 | — | 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 28 – May 5 | Jun 2 – Jun 16 | Jun 2 – Jun 9 | — | 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 2 – Jun 16 | — | — | 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 28 – May 5 | — | Jun 9 – Jun 16 | — | 70–90 days | Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost. |
| Cantaloupe | Apr 28 – May 5 | — | Jun 9 – Jun 16 | — | 70–90 days | Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting. |
| Corn | — | May 26 – Jun 9 | — | — | 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 26 – Jun 9 | — | — | 50–65 days | Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush. |
| Pea | — | Apr 14 – Apr 28 | — | — | 55–70 days | Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Lettuce | — | Apr 28 – May 12 | — | Jul 28 – Aug 11 | 45–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts. |
| Spinach | — | Apr 14 – Apr 28 | — | Jul 28 – Aug 11 | 40–50 days | Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Kale | — | Apr 28 – May 12 | — | Jul 14 – Jul 28 | 50–65 days | Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants. |
| Arugula | — | Apr 28 – May 12 | — | Aug 11 – Aug 18 | 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 5 – May 19 | — | — | 50–60 days | Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too. |
| Broccoli | Apr 7 – Apr 21 | — | May 5 – May 12 | Jul 21 – Jul 28 | 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 7 – Apr 21 | — | May 12 – May 19 | Jul 14 – Jul 21 | 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 7 – Apr 21 | — | Apr 28 – May 12 | Jul 14 – Jul 28 | 60–100 days | Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost. |
| Brussels Sprouts | Apr 7 – Apr 21 | — | May 5 – May 19 | — | 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 28 – May 12 | — | Jun 30 – Jul 14 | 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 28 – May 12 | — | Jul 14 – Jul 28 | 50–65 days | Direct sow 2-4 weeks before last frost; tolerates light frost. |
| Radish | — | Apr 21 – May 5 | — | Aug 11 – Aug 25 | 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 28 – May 12 | — | Jul 14 – Jul 28 | 40–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. |
| Onion | Mar 17 – Mar 31 | — | Apr 28 – May 12 | — | 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 25 – Sep 8 | 240–270 days | Fall-planted crop only; not planted in spring in most climates. |
| Potato | — | Apr 28 – May 12 | — | — | 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 9 – Jun 23 | — | 90–120 days | Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive. |
| Asparagus | — | — | Apr 28 – May 12 | — | 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 14 – Apr 21 | — | Jun 2 – Jun 9 | — | 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 5 – May 19 | — | Jul 28 – Aug 11 | 45–70 days | Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring. |
| Parsley | Mar 31 – Apr 14 | — | May 12 – May 19 | — | 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 5 – May 19 | — | — | 40–60 days | Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer. |
| Oregano | Mar 31 – Apr 14 | — | May 26 – Jun 2 | — | 80–90 days | Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date. |
| Thyme | Mar 31 – Apr 14 | — | May 26 – Jun 2 | — | 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 2 – Jun 16 | — | — | 70–100 days | Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting. |
| Zinnia | Apr 28 – May 5 | Jun 2 – Jun 16 | Jun 2 – Jun 9 | — | 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 14 – Apr 28 | — | Jun 2 – Jun 9 | — | 45–60 days | Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed. |
| Cosmos | Apr 28 – May 5 | Jun 2 – Jun 16 | Jun 2 – Jun 9 | — | 60–90 days | Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early. |
| Nasturtium | — | Jun 2 – Jun 16 | — | — | 50–65 days | Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed. |
| Dahlia | — | — | Jun 2 – Jun 16 | — | 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 Bozeman, MT?
Based on 1991–2020 NOAA climate normals for the BOZEMAN MONTANA STATE UNIV, MT US station, the last spring frost in Bozeman typically falls around May 26. A cautious gardener might wait until June 14 (only a 10% chance of a later frost), while May 9 marks an earlier, higher-risk planting date.
When is the first frost in Bozeman, MT in fall?
The first fall frost in Bozeman typically arrives around September 22. To stay safe, assume frost could start as early as September 5; in milder years it can hold off until October 5.
How long is the growing season in Bozeman, MT?
Bozeman's average frost-free growing season is about 116 days, running from the typical last spring frost (May 26) to the typical first fall frost (September 22).
What USDA hardiness zone is Bozeman, MT in?
Bozeman, 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.