Frost Dates for Thief River Falls, MN 56701
Last spring frost May 12 · First fall frost September 21 · 132 frost-free days · USDA Zone 4a
ZIP 56701 has about 12,700 people.
Moderate season: 132 frost-free days. Spring frost risk spans April 28–May 25 (27 days). Fall frost risk spans September 7–October 5 (28 days).
Frost probability for 56701
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 25 | May 12 | April 28 |
| Fall (first frost) | September 7 | September 21 | October 5 |
Dates come from NOAA 1971–2000 freeze probabilities at AGASSIZ REFUGE (25.7 km away); the 50% date is the median year.
Which crops fit a 132-day season in Thief River Falls
In Thief River Falls (132 frost-free days, a moderate season), 37 of 56 planner crops fit outright, 16 get two plantings, 2 need an indoor start, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Apr 7 | May 26–Jun 2 | 90 | fits: 80 days to maturity, 90 available after May 26. | — |
| Pepper | Mar 31 | May 26–Jun 2 | 90 | fits: 75 days to maturity, 90 available after May 26. | May 27 |
| Lettuce | Mar 17 | Apr 14–Apr 21 | 167 | two-plantings: Plant Apr 14 and again by Jul 31; both mature before Sep 28. | Jul 31 |
| Carrots | — | Apr 21–Apr 28 | 174 | fits: 70 days to maturity, 174 available after Apr 21. | Jul 20 |
| Cucumber | Apr 21 | May 26–Jun 2 | 104 | fits: 60 days to maturity, 104 available after May 26. | Jun 25 |
| Beans | — | May 19–Jun 2 | 118 | fits: 60 days to maturity, 118 available after May 19. | Jul 2 |
| Peas | — | Mar 17–May 26 | 195 | fits: 65 days to maturity, 195 available after Mar 17. | Jul 11 |
| Zucchini | Apr 28 | May 26–Jun 2 | 104 | fits: 55 days to maturity, 104 available after May 26. | Jun 30 |
| Onion | Feb 17 | Apr 14–Apr 28 | 167 | fits: 100 days to maturity, 167 available after Apr 14. | — |
| Spinach | — | Mar 17–May 5 | 209 | two-plantings: Plant Mar 17 and again by Aug 19; both mature before Oct 12. | Aug 19 |
| Kale | Mar 3 | Apr 14–Apr 28 | 181 | two-plantings: Plant Apr 14 and again by Aug 4; both mature before Oct 12. | Aug 4 |
| Broccoli | Mar 17 | Apr 14–Apr 28 | 167 | fits: 80 days to maturity, 167 available after Apr 14. | Jun 26 |
| Cabbage | Mar 17 | Apr 14–Apr 28 | 181 | fits: 70 days to maturity, 181 available after Apr 14. | Jul 20 |
| Radish | — | Mar 17–Jun 9 | 195 | two-plantings: Plant Mar 17 and again by Aug 20; both mature before Sep 28. | Aug 20 |
| Beets | — | Mar 17–Jun 9 | 195 | two-plantings: Plant Mar 17 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Potatoes | — | Apr 28–May 5 | 153 | fits: 90 days to maturity, 153 available after Apr 28. | — |
| Garlic | — | Sep 21 | 237 | overwinter: Plant Sep 21 to Oct 12; harvest the following summer. | Oct 12 |
| Strawberry | — | Apr 7–Jun 2 | 188 | perennial: A perennial: plant Apr 7; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 14 | May 19–May 26 | 104 | fits: 75 days to maturity, 104 available after May 19. | Jun 3 |
| Pumpkin | Apr 28 | May 26–May 26 | 97 | head-start: Even planted out May 26, the outdoor season is about 3 days short; choose an early variety or grow under cover. | — |
| Cauliflower | Mar 31 | May 5–May 19 | 146 | fits: 75 days to maturity, 146 available after May 5. | Jul 1 |
| Swiss Chard | Mar 17 | Apr 28–Apr 28 | 153 | two-plantings: Plant Apr 28 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Arugula | — | Mar 17–Jun 9 | 209 | two-plantings: Plant Mar 17 and again by Aug 19; both mature before Oct 12. | Aug 19 |
| Brussel Sprouts | Mar 17 | Apr 14–Apr 28 | 181 | fits: 100 days to maturity, 181 available after Apr 14. | Jun 20 |
| Butternut Squash | Apr 28 | May 26–Jun 2 | 97 | head-start: Even planted out May 26, the outdoor season is about 3 days short; choose an early variety or grow under cover. | — |
| Eggplant | Mar 24 | May 26–Jun 2 | 90 | fits: 70 days to maturity, 90 available after May 26. | Jun 1 |
| Okra | Apr 14 | May 19–May 26 | 111 | fits: 55 days to maturity, 111 available after May 19. | Jun 30 |
| Basil | Apr 7 | Jun 2–Jun 2 | 97 | fits: 60 days to maturity, 97 available after Jun 2. | Jun 25 |
| Cilantro | — | Apr 14–May 5 | 167 | two-plantings: Plant Apr 14 and again by Jul 26; both mature before Sep 28. | Jul 26 |
| Parsley | Mar 3 | May 19–May 26 | 132 | fits: 70 days to maturity, 132 available after May 19. | Jul 6 |
| Celery | Mar 3 | May 19–Jun 2 | 132 | fits: 120 days to maturity, 132 available after May 19. | — |
| Scallions | Mar 3 | Apr 14–Apr 28 | 181 | two-plantings: Plant Apr 14 and again by Jul 30; both mature before Oct 12. | Jul 30 |
| Turnip | — | Apr 14–Apr 28 | 181 | two-plantings: Plant Apr 14 and again by Aug 9; both mature before Oct 12. | Aug 9 |
| Kohlrabi | — | Mar 31–Apr 14 | 195 | two-plantings: Plant Mar 31 and again by Aug 4; both mature before Oct 12. | Aug 4 |
| Bok Choy | Apr 14 | May 5–May 12 | 146 | two-plantings: Plant May 5 and again by Jul 31; both mature before Sep 28. | Jul 31 |
| Collards | Mar 3 | Apr 14–Apr 28 | 181 | two-plantings: Plant Apr 14 and again by Jul 30; both mature before Oct 12. | Jul 30 |
| Cantaloupe | Apr 28 | May 26–Jun 2 | 90 | fits: 85 days to maturity, 90 available after May 26. | — |
| Chives | Feb 17 | May 19–May 26 | 146 | fits: 90 days to maturity, 146 available after May 19. | — |
| Dill | — | Mar 17–Jun 9 | 195 | two-plantings: Plant Mar 17 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Oregano | Mar 3 | May 19–May 26 | 146 | fits: 80 days to maturity, 146 available after May 19. | — |
| Rosemary | Feb 17 | May 19–May 26 | 132 | fits: 80 days to maturity, 132 available after May 19. | — |
| Sage | Mar 17 | May 19–May 26 | 146 | fits: 75 days to maturity, 146 available after May 19. | — |
| Thyme | Mar 3 | May 19–May 26 | 146 | fits: 90 days to maturity, 146 available after May 19. | — |
| Calendula | Mar 31 | Apr 28–May 12 | 153 | two-plantings: Plant Apr 28 and again by Jul 26; both mature before Sep 28. | Jul 26 |
| Cosmos | Apr 14 | May 12–May 26 | 118 | fits: 60 days to maturity, 118 available after May 12. | Jun 25 |
| Lavender | Feb 17 | May 12–May 26 | 153 | fits: 90 days to maturity, 153 available after May 12. | — |
| Marigolds | Mar 31 | May 12–May 19 | 118 | two-plantings: Plant May 12 and again by Jul 5; both mature before Sep 7. | Jul 5 |
| Melons | Apr 28 | May 26–Jun 2 | 90 | fits: 85 days to maturity, 90 available after May 26. | — |
| Mint | — | May 12–May 26 | 153 | fits: 90 days to maturity, 153 available after May 12. | — |
| Nasturtiums | Apr 14 | May 12–May 19 | 118 | fits: 55 days to maturity, 118 available after May 12. | Jun 30 |
| Pole Beans | — | May 19–Jun 2 | 111 | fits: 65 days to maturity, 111 available after May 19. | Jun 20 |
| Spaghetti Squash | Apr 28 | May 26–Jun 2 | 97 | fits: 90 days to maturity, 97 available after May 26. | — |
| Sunflowers | — | May 12–May 26 | 118 | fits: 70 days to maturity, 118 available after May 12. | Jun 15 |
| Tomatillos | Mar 17 | May 19–May 26 | 97 | fits: 75 days to maturity, 97 available after May 19. | May 27 |
| Watermelon | Apr 28 | May 19–May 26 | 97 | fits: 80 days to maturity, 97 available after May 19. | May 22 |
| Yellow Squash | Apr 28 | May 26–Jun 2 | 104 | fits: 55 days to maturity, 104 available after May 26. | Jun 30 |
| Zinnias | Apr 14 | May 12–May 26 | 118 | fits: 60 days to maturity, 118 available after May 12. | Jun 25 |
Month by month in Thief River Falls
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 17), Lavender (Feb 17), Onion (Feb 17), Rosemary (Feb 17). |
| March | Start indoors: Celery (Mar 3), Collards (Mar 3), Kale (Mar 3), Oregano (Mar 3), Parsley (Mar 3), Scallions (Mar 3), +13 more. Direct sow from: Arugula (Mar 17), Beets (Mar 17), Dill (Mar 17), Peas (Mar 17), Radish (Mar 17), Spinach (Mar 17), +1 more. |
| April | Start indoors: Basil (Apr 7), Tomato (Apr 7), Bok Choy (Apr 14), Corn (Apr 14), Cosmos (Apr 14), Nasturtiums (Apr 14), +11 more. Direct sow from: Cilantro (Apr 14), Turnip (Apr 14), Carrots (Apr 21), Potatoes (Apr 28). Transplant from: Broccoli (Apr 14), Brussel Sprouts (Apr 14), Cabbage (Apr 14), Collards (Apr 14), Kale (Apr 14), Lettuce (Apr 14), +4 more. Plant: Strawberry (Apr 7). |
| May | Direct sow from: Sunflowers (May 12), Beans (May 19), Pole Beans (May 19). Transplant from: Bok Choy (May 5), Cauliflower (May 5), Cosmos (May 12), Lavender (May 12), Marigolds (May 12), Mint (May 12), +24 more. Last frost around May 12. Last sowing dates: Watermelon (May 22), Pepper (May 27), Tomatillos (May 27). |
| June | Transplant from: Basil (Jun 2). Last sowing dates: Eggplant (Jun 1), Corn (Jun 3), Sunflowers (Jun 15), Brussel Sprouts (Jun 20), Pole Beans (Jun 20), Basil (Jun 25), +8 more. |
| July | Last sowing dates: Cauliflower (Jul 1), Beans (Jul 2), Marigolds (Jul 5), Parsley (Jul 6), Peas (Jul 11), Cabbage (Jul 20), +10 more. |
| August | Last sowing dates: Kale (Aug 4), Kohlrabi (Aug 4), Turnip (Aug 9), Arugula (Aug 19), Spinach (Aug 19), Radish (Aug 20). |
| September | Direct sow from: Garlic (Sep 21). First frost around September 21. |
| October | Last sowing dates: Garlic (Oct 12). |
| 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 Thief River Falls, MN (ZIP 56701)?
The median last spring frost date for Thief River Falls, MN (ZIP code 56701) is around May 12. 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 28; one in ten it runs past May 25.
What is the first fall frost date in Thief River Falls, MN?
The median first fall frost date for Thief River Falls, MN is around September 21. 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 7 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Thief River Falls, MN?
The frost-free growing season in Thief River Falls is about 132 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 Thief River Falls (132 frost-free days, a moderate season), 37 of 56 planner crops fit outright, 16 get two plantings, 2 need an indoor start, 1 crop is perennial.
What USDA hardiness zone is Thief River Falls, MN?
Thief River Falls, MN 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 Thief River Falls, MN?
Start tomatoes indoors Apr 7 and plant out May 26 in Thief River Falls. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Thief River Falls?
Two: plant Apr 14 and again by Jul 31; both mature before Sep 28.
When do I plant garlic in Thief River Falls?
Sep 21 to Oct 12; it overwinters and is ready the following summer.
Can I grow Butternut Squash in Thief River Falls?
Yes, with help. Even planted out May 26, the outdoor season is about 3 days short; choose an early variety or grow under cover.
Which nearby ZIP has a longer season?
Grand Forks (ZIP 58201) has 140 frost-free days, 8 more than Thief River Falls (ZIP 56701). See Grand Forks ZIP 58201 frost dates
Nearby and related
- Frost dates for East Grand Forks, MN 56721 (35.8 mi)
- Frost dates for Grand Forks, ND 58201 (46.7 mi)
- Frost dates for Bemidji, MN 56601 (75.1 mi)
- Frost dates for Detroit Lakes, MN 56501 (90.3 mi)
- Frost dates for Park Rapids, MN 56470 (91.2 mi)
- When to plant in MN
- When to plant Peppers in MN
- When to plant Cucumbers in MN
- When to plant Zucchini in MN
- When to plant Butternut Squash in MN
- When to plant Basil in MN
- When to plant Sweet Corn in MN
- Look up another ZIP