Frost Dates & Planting Calendar for Mandan, ND
Plan your garden around Mandan, ND's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.
Last Spring Frost
May 13
Safe May 26
Typical May 13
Risky May 1
First Fall Frost
September 27
Safe Sep 15
Typical Sep 27
Risky Oct 10
Growing Season
136 days
Typical last frost to typical first frost.
USDA Hardiness Zone
Zone 4a
Very cold winters, focus on short-season varieties and cold-hardy perennials.
Data: NOAA station MANDAN EXP STN, ND US, 2.2 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 18 – Apr 1 | — | May 20 – May 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 | Mar 4 – Mar 18 | — | May 20 – Jun 3 | — | 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 4 – Mar 18 | — | May 27 – Jun 3 | — | 65–85 days | Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant. |
| Cucumber | Apr 15 – Apr 22 | May 20 – May 27 | May 20 – May 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 | Apr 22 – Apr 29 | May 20 – Jun 3 | May 20 – May 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 | Apr 15 – Apr 22 | May 20 – Jun 3 | May 20 – May 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 | — | May 20 – Jun 3 | — | — | 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 15 – Apr 22 | — | May 27 – Jun 3 | — | 70–90 days | Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost. |
| Cantaloupe | Apr 15 – Apr 22 | — | May 27 – Jun 3 | — | 70–90 days | Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting. |
| Corn | — | May 13 – May 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 | — | May 13 – May 27 | — | — | 50–65 days | Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush. |
| Pea | — | Apr 1 – Apr 15 | — | — | 55–70 days | Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Lettuce | — | Apr 15 – Apr 29 | — | Aug 2 – Aug 16 | 45–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts. |
| Spinach | — | Apr 1 – Apr 15 | — | Aug 2 – Aug 16 | 40–50 days | Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Kale | — | Apr 15 – Apr 29 | — | Jul 19 – Aug 2 | 50–65 days | Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants. |
| Arugula | — | Apr 15 – Apr 29 | — | Aug 16 – Aug 23 | 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 22 – May 6 | — | — | 50–60 days | Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too. |
| Broccoli | Mar 25 – Apr 8 | — | Apr 22 – Apr 29 | Jul 26 – Aug 2 | 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 25 – Apr 8 | — | Apr 29 – May 6 | Jul 19 – Jul 26 | 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 25 – Apr 8 | — | Apr 15 – Apr 29 | Jul 19 – Aug 2 | 60–100 days | Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost. |
| Brussels Sprouts | Mar 25 – Apr 8 | — | Apr 22 – May 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 | — | Apr 15 – Apr 29 | — | Jul 5 – Jul 19 | 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 15 – Apr 29 | — | Jul 19 – Aug 2 | 50–65 days | Direct sow 2-4 weeks before last frost; tolerates light frost. |
| Radish | — | Apr 8 – Apr 22 | — | Aug 16 – Aug 30 | 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 15 – Apr 29 | — | Jul 19 – Aug 2 | 40–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. |
| Onion | Mar 4 – Mar 18 | — | Apr 15 – Apr 29 | — | 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 30 – Sep 13 | 240–270 days | Fall-planted crop only; not planted in spring in most climates. |
| Potato | — | Apr 15 – Apr 29 | — | — | 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 27 – Jun 10 | — | 90–120 days | Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive. |
| Asparagus | — | — | Apr 15 – Apr 29 | — | 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 1 – Apr 8 | — | May 20 – May 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 | — | Apr 22 – May 6 | — | Aug 2 – Aug 16 | 45–70 days | Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring. |
| Parsley | Mar 18 – Apr 1 | — | Apr 29 – May 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 | — | Apr 22 – May 6 | — | — | 40–60 days | Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer. |
| Oregano | Mar 18 – Apr 1 | — | May 13 – May 20 | — | 80–90 days | Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date. |
| Thyme | Mar 18 – Apr 1 | — | May 13 – May 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 | — | May 20 – Jun 3 | — | — | 70–100 days | Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting. |
| Zinnia | Apr 15 – Apr 22 | May 20 – Jun 3 | May 20 – May 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 | Apr 1 – Apr 15 | — | May 20 – May 27 | — | 45–60 days | Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed. |
| Cosmos | Apr 15 – Apr 22 | May 20 – Jun 3 | May 20 – May 27 | — | 60–90 days | Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early. |
| Nasturtium | — | May 20 – Jun 3 | — | — | 50–65 days | Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed. |
| Dahlia | — | — | May 20 – Jun 3 | — | 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 Mandan, ND?
Based on 1991–2020 NOAA climate normals for the MANDAN EXP STN, ND US station, the last spring frost in Mandan typically falls around May 13. A cautious gardener might wait until May 26 (only a 10% chance of a later frost), while May 1 marks an earlier, higher-risk planting date.
When is the first frost in Mandan, ND in fall?
The first fall frost in Mandan typically arrives around September 27. To stay safe, assume frost could start as early as September 15; in milder years it can hold off until October 10.
How long is the growing season in Mandan, ND?
Mandan's average frost-free growing season is about 136 days, running from the typical last spring frost (May 13) to the typical first fall frost (September 27).
What USDA hardiness zone is Mandan, ND in?
Mandan, ND is in USDA plant hardiness zone 4a, per the USDA's 2023 Plant Hardiness Zone Map. Very cold winters, focus on short-season varieties and cold-hardy perennials.