Frost Dates for Grand Forks, ND 58201
Last spring frost May 10 · First fall frost September 27 · 140 frost-free days · USDA Zone 4a
ZIP 58201 has about 42,400 people, the largest of 3 ZIP codes in Grand Forks.
Moderate season: 140 frost-free days. Spring frost risk spans April 24–May 22 (28 days). Fall frost risk spans September 17–October 7 (20 days).
Frost probability for 58201
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 22 | May 10 | April 24 |
| Fall (first frost) | September 17 | September 27 | October 7 |
Dates come from NOAA 1971–2000 freeze probabilities at GRAND FORKS UNIV (NWS) (6.6 km away); the 50% date is the median year.
Frost dates by ZIP code in Grand Forks, ND
| ZIP | Last spring frost (50%) | First fall frost (50%) | Zone |
|---|---|---|---|
| 58201 | May 10 | September 27 | 4a |
| 58203 | May 12 | September 21 | 4a |
| 58202 | May 11 | September 23 | 5b (est.) |
Which crops fit a 140-day season in Grand Forks
In Grand Forks (140 frost-free days, a moderate season), 38 of 56 planner crops fit outright, 17 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Apr 5 | May 24–May 31 | 98 | fits: 80 days to maturity, 98 available after May 24. | May 28 |
| Pepper | Mar 29 | May 24–May 31 | 98 | fits: 75 days to maturity, 98 available after May 24. | Jun 2 |
| Lettuce | Mar 15 | Apr 12–Apr 19 | 175 | two-plantings: Plant Apr 12 and again by Aug 6; both mature before Oct 4. | Aug 6 |
| Carrots | — | Apr 19–Apr 26 | 182 | fits: 70 days to maturity, 182 available after Apr 19. | Jul 26 |
| Cucumber | Apr 19 | May 24–May 31 | 112 | fits: 60 days to maturity, 112 available after May 24. | Jul 1 |
| Beans | — | May 17–May 31 | 126 | fits: 60 days to maturity, 126 available after May 17. | Jul 8 |
| Peas | — | Mar 15–May 24 | 203 | fits: 65 days to maturity, 203 available after Mar 15. | Jul 17 |
| Zucchini | Apr 26 | May 24–May 31 | 112 | fits: 55 days to maturity, 112 available after May 24. | Jul 6 |
| Onion | Feb 15 | Apr 12–Apr 26 | 175 | fits: 100 days to maturity, 175 available after Apr 12. | — |
| Spinach | — | Mar 15–May 3 | 217 | two-plantings: Plant Mar 15 and again by Aug 25; both mature before Oct 18. | Aug 25 |
| Kale | Mar 1 | Apr 12–Apr 26 | 189 | two-plantings: Plant Apr 12 and again by Aug 10; both mature before Oct 18. | Aug 10 |
| Broccoli | Mar 15 | Apr 12–Apr 26 | 175 | fits: 80 days to maturity, 175 available after Apr 12. | Jul 2 |
| Cabbage | Mar 15 | Apr 12–Apr 26 | 189 | fits: 70 days to maturity, 189 available after Apr 12. | Jul 26 |
| Radish | — | Mar 15–Jun 7 | 203 | two-plantings: Plant Mar 15 and again by Aug 26; both mature before Oct 4. | Aug 26 |
| Beets | — | Mar 15–Jun 7 | 203 | two-plantings: Plant Mar 15 and again by Jul 27; both mature before Oct 4. | Jul 27 |
| Potatoes | — | Apr 26–May 3 | 161 | fits: 90 days to maturity, 161 available after Apr 26. | — |
| Garlic | — | Sep 27 | 245 | overwinter: Plant Sep 27 to Oct 18; harvest the following summer. | Oct 18 |
| Strawberry | — | Apr 5–May 31 | 196 | perennial: A perennial: plant Apr 5; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 12 | May 17–May 24 | 112 | fits: 75 days to maturity, 112 available after May 17. | Jun 9 |
| Pumpkin | Apr 26 | May 24–May 24 | 105 | fits: 100 days to maturity, 105 available after May 24. | — |
| Cauliflower | Mar 29 | May 3–May 17 | 154 | fits: 75 days to maturity, 154 available after May 3. | Jul 7 |
| Swiss Chard | Mar 15 | Apr 26–Apr 26 | 161 | two-plantings: Plant Apr 26 and again by Jul 27; both mature before Oct 4. | Jul 27 |
| Arugula | — | Mar 15–Jun 7 | 217 | two-plantings: Plant Mar 15 and again by Aug 25; both mature before Oct 18. | Aug 25 |
| Brussel Sprouts | Mar 15 | Apr 12–Apr 26 | 189 | fits: 100 days to maturity, 189 available after Apr 12. | Jun 26 |
| Butternut Squash | Apr 26 | May 24–May 31 | 105 | fits: 100 days to maturity, 105 available after May 24. | — |
| Eggplant | Mar 22 | May 24–May 31 | 98 | fits: 70 days to maturity, 98 available after May 24. | Jun 7 |
| Okra | Apr 12 | May 17–May 24 | 119 | fits: 55 days to maturity, 119 available after May 17. | Jul 6 |
| Basil | Apr 5 | May 31–May 31 | 105 | fits: 60 days to maturity, 105 available after May 31. | Jul 1 |
| Cilantro | — | Apr 12–May 3 | 175 | two-plantings: Plant Apr 12 and again by Aug 1; both mature before Oct 4. | Aug 1 |
| Parsley | Mar 1 | May 17–May 24 | 140 | fits: 70 days to maturity, 140 available after May 17. | Jul 12 |
| Celery | Mar 1 | May 17–May 31 | 140 | fits: 120 days to maturity, 140 available after May 17. | May 23 |
| Scallions | Mar 1 | Apr 12–Apr 26 | 189 | two-plantings: Plant Apr 12 and again by Aug 5; both mature before Oct 18. | Aug 5 |
| Turnip | — | Apr 12–Apr 26 | 189 | two-plantings: Plant Apr 12 and again by Aug 15; both mature before Oct 18. | Aug 15 |
| Kohlrabi | — | Mar 29–Apr 12 | 203 | two-plantings: Plant Mar 29 and again by Aug 10; both mature before Oct 18. | Aug 10 |
| Bok Choy | Apr 12 | May 3–May 10 | 154 | two-plantings: Plant May 3 and again by Aug 6; both mature before Oct 4. | Aug 6 |
| Collards | Mar 1 | Apr 12–Apr 26 | 189 | two-plantings: Plant Apr 12 and again by Aug 5; both mature before Oct 18. | Aug 5 |
| Cantaloupe | Apr 26 | May 24–May 31 | 98 | fits: 85 days to maturity, 98 available after May 24. | — |
| Chives | Feb 15 | May 17–May 24 | 154 | fits: 90 days to maturity, 154 available after May 17. | — |
| Dill | — | Mar 15–Jun 7 | 203 | two-plantings: Plant Mar 15 and again by Jul 27; both mature before Oct 4. | Jul 27 |
| Oregano | Mar 1 | May 17–May 24 | 154 | fits: 80 days to maturity, 154 available after May 17. | — |
| Rosemary | Feb 15 | May 17–May 24 | 140 | fits: 80 days to maturity, 140 available after May 17. | — |
| Sage | Mar 15 | May 17–May 24 | 154 | fits: 75 days to maturity, 154 available after May 17. | — |
| Thyme | Mar 1 | May 17–May 24 | 154 | fits: 90 days to maturity, 154 available after May 17. | — |
| Calendula | Mar 29 | Apr 26–May 10 | 161 | two-plantings: Plant Apr 26 and again by Aug 1; both mature before Oct 4. | Aug 1 |
| Cosmos | Apr 12 | May 10–May 24 | 126 | fits: 60 days to maturity, 126 available after May 10. | Jul 1 |
| Lavender | Feb 15 | May 10–May 24 | 161 | fits: 90 days to maturity, 161 available after May 10. | — |
| Marigolds | Mar 29 | May 10–May 17 | 126 | two-plantings: Plant May 10 and again by Jul 11; both mature before Sep 13. | Jul 11 |
| Melons | Apr 26 | May 24–May 31 | 98 | fits: 85 days to maturity, 98 available after May 24. | — |
| Mint | — | May 10–May 24 | 161 | fits: 90 days to maturity, 161 available after May 10. | — |
| Nasturtiums | Apr 12 | May 10–May 17 | 126 | two-plantings: Plant May 10 and again by Jul 6; both mature before Sep 13. | Jul 6 |
| Pole Beans | — | May 17–May 31 | 119 | fits: 65 days to maturity, 119 available after May 17. | Jun 26 |
| Spaghetti Squash | Apr 26 | May 24–May 31 | 105 | fits: 90 days to maturity, 105 available after May 24. | May 25 |
| Sunflowers | — | May 10–May 24 | 126 | fits: 70 days to maturity, 126 available after May 10. | Jun 21 |
| Tomatillos | Mar 15 | May 17–May 24 | 105 | fits: 75 days to maturity, 105 available after May 17. | Jun 2 |
| Watermelon | Apr 26 | May 17–May 24 | 105 | fits: 80 days to maturity, 105 available after May 17. | May 28 |
| Yellow Squash | Apr 26 | May 24–May 31 | 112 | fits: 55 days to maturity, 112 available after May 24. | Jul 6 |
| Zinnias | Apr 12 | May 10–May 24 | 126 | fits: 60 days to maturity, 126 available after May 10. | Jul 1 |
Month by month in Grand Forks
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 15), Lavender (Feb 15), Onion (Feb 15), Rosemary (Feb 15). |
| March | Start indoors: Celery (Mar 1), Collards (Mar 1), Kale (Mar 1), Oregano (Mar 1), Parsley (Mar 1), Scallions (Mar 1), +13 more. Direct sow from: Arugula (Mar 15), Beets (Mar 15), Dill (Mar 15), Peas (Mar 15), Radish (Mar 15), Spinach (Mar 15), +1 more. |
| April | Start indoors: Basil (Apr 5), Tomato (Apr 5), Bok Choy (Apr 12), Corn (Apr 12), Cosmos (Apr 12), Nasturtiums (Apr 12), +11 more. Direct sow from: Cilantro (Apr 12), Turnip (Apr 12), Carrots (Apr 19), Potatoes (Apr 26). Transplant from: Broccoli (Apr 12), Brussel Sprouts (Apr 12), Cabbage (Apr 12), Collards (Apr 12), Kale (Apr 12), Lettuce (Apr 12), +4 more. Plant: Strawberry (Apr 5). |
| May | Direct sow from: Sunflowers (May 10), Beans (May 17), Pole Beans (May 17). Transplant from: Bok Choy (May 3), Cauliflower (May 3), Cosmos (May 10), Lavender (May 10), Marigolds (May 10), Mint (May 10), +25 more. Last frost around May 10. Last sowing dates: Celery (May 23), Spaghetti Squash (May 25), Tomato (May 28), Watermelon (May 28). |
| June | Last sowing dates: Pepper (Jun 2), Tomatillos (Jun 2), Eggplant (Jun 7), Corn (Jun 9), Sunflowers (Jun 21), Brussel Sprouts (Jun 26), +1 more. |
| July | Last sowing dates: Basil (Jul 1), Cosmos (Jul 1), Cucumber (Jul 1), Zinnias (Jul 1), Broccoli (Jul 2), Nasturtiums (Jul 6), +13 more. |
| August | Last sowing dates: Calendula (Aug 1), Cilantro (Aug 1), Collards (Aug 5), Scallions (Aug 5), Bok Choy (Aug 6), Lettuce (Aug 6), +6 more. |
| September | Direct sow from: Garlic (Sep 27). First frost around September 27. |
| October | Last sowing dates: Garlic (Oct 18). |
| November | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Grand Forks, ND (ZIP 58201)?
The median last spring frost date for Grand Forks, ND (ZIP code 58201) is around May 10. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before April 24; one in ten it runs past May 22.
What is the first fall frost date in Grand Forks, ND?
The median first fall frost date for Grand Forks, ND is around September 27. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around September 17 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Grand Forks, ND?
The frost-free growing season in Grand Forks is about 140 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Grand Forks (140 frost-free days, a moderate season), 38 of 56 planner crops fit outright, 17 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Grand Forks, ND?
Grand Forks, ND is in USDA hardiness zone 4a (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Grand Forks, ND?
Start tomatoes indoors Apr 5 and plant out May 24 in Grand Forks. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Grand Forks?
Two: plant Apr 12 and again by Aug 6; both mature before Oct 4.
When do I plant garlic in Grand Forks?
Sep 27 to Oct 18; it overwinters and is ready the following summer.
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