Frost Dates & Planting Calendar for Duluth, MN
Plan your garden around Duluth, MN's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.
Last Spring Frost
May 14
Safe Jun 1
Typical May 14
Risky Apr 24
First Fall Frost
October 12
Safe Sep 25
Typical Oct 12
Risky Oct 26
Growing Season
149 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 DULUTH HARBOR STN, MN US, 2.1 km away.
—
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 19 – Apr 2 | — | May 21 – May 28 | — | 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 5 – Mar 19 | — | May 21 – Jun 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 | Mar 5 – Mar 19 | — | May 28 – Jun 4 | — | 65–85 days | Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant. |
| Cucumber | Apr 16 – Apr 23 | May 21 – May 28 | May 21 – May 28 | — | 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 23 – Apr 30 | May 21 – Jun 4 | May 21 – May 28 | — | 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 16 – Apr 23 | May 21 – Jun 4 | May 21 – May 28 | — | 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 21 – Jun 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 | Apr 16 – Apr 23 | — | May 28 – Jun 4 | — | 70–90 days | Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost. |
| Cantaloupe | Apr 16 – Apr 23 | — | May 28 – Jun 4 | — | 70–90 days | Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting. |
| Corn | — | May 14 – May 28 | — | — | 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 14 – May 28 | — | — | 50–65 days | Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush. |
| Pea | — | Apr 2 – Apr 16 | — | — | 55–70 days | Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Lettuce | — | Apr 16 – Apr 30 | — | Aug 17 – Aug 31 | 45–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts. |
| Spinach | — | Apr 2 – Apr 16 | — | Aug 17 – Aug 31 | 40–50 days | Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Kale | — | Apr 16 – Apr 30 | — | Aug 3 – Aug 17 | 50–65 days | Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants. |
| Arugula | — | Apr 16 – Apr 30 | — | Aug 31 – Sep 7 | 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 23 – May 7 | — | — | 50–60 days | Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too. |
| Broccoli | Mar 26 – Apr 9 | — | Apr 23 – Apr 30 | Aug 10 – Aug 17 | 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 26 – Apr 9 | — | Apr 30 – May 7 | Aug 3 – Aug 10 | 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 26 – Apr 9 | — | Apr 16 – Apr 30 | Aug 3 – Aug 17 | 60–100 days | Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost. |
| Brussels Sprouts | Mar 26 – Apr 9 | — | Apr 23 – May 7 | — | 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 16 – Apr 30 | — | Jul 20 – Aug 3 | 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 16 – Apr 30 | — | Aug 3 – Aug 17 | 50–65 days | Direct sow 2-4 weeks before last frost; tolerates light frost. |
| Radish | — | Apr 9 – Apr 23 | — | Aug 31 – Sep 14 | 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 16 – Apr 30 | — | Aug 3 – Aug 17 | 40–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. |
| Onion | Mar 5 – Mar 19 | — | Apr 16 – Apr 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 | — | — | — | Sep 14 – Sep 28 | 240–270 days | Fall-planted crop only; not planted in spring in most climates. |
| Potato | — | Apr 16 – Apr 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 | — | — | May 28 – Jun 11 | — | 90–120 days | Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive. |
| Asparagus | — | — | Apr 16 – Apr 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 | Apr 2 – Apr 9 | — | May 21 – May 28 | — | 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 23 – May 7 | — | Aug 17 – Aug 31 | 45–70 days | Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring. |
| Parsley | Mar 19 – Apr 2 | — | Apr 30 – May 7 | — | 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 23 – May 7 | — | — | 40–60 days | Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer. |
| Oregano | Mar 19 – Apr 2 | — | May 14 – May 21 | — | 80–90 days | Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date. |
| Thyme | Mar 19 – Apr 2 | — | May 14 – May 21 | — | 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 21 – Jun 4 | — | — | 70–100 days | Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting. |
| Zinnia | Apr 16 – Apr 23 | May 21 – Jun 4 | May 21 – May 28 | — | 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 2 – Apr 16 | — | May 21 – May 28 | — | 45–60 days | Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed. |
| Cosmos | Apr 16 – Apr 23 | May 21 – Jun 4 | May 21 – May 28 | — | 60–90 days | Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early. |
| Nasturtium | — | May 21 – Jun 4 | — | — | 50–65 days | Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed. |
| Dahlia | — | — | May 21 – Jun 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 Duluth, MN?
Based on 1991–2020 NOAA climate normals for the DULUTH HARBOR STN, MN US station, the last spring frost in Duluth typically falls around May 14. A cautious gardener might wait until June 1 (only a 10% chance of a later frost), while April 24 marks an earlier, higher-risk planting date.
When is the first frost in Duluth, MN in fall?
The first fall frost in Duluth typically arrives around October 12. To stay safe, assume frost could start as early as September 25; in milder years it can hold off until October 26.
How long is the growing season in Duluth, MN?
Duluth's average frost-free growing season is about 149 days, running from the typical last spring frost (May 14) to the typical first fall frost (October 12).
What USDA hardiness zone is Duluth, MN in?
Duluth, MN 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.