Grand Forks, North Dakota planting calendar and frost dates
Grand Forks is in USDA hardiness zone 4a. The last spring frost typically comes around May 10 and the first fall frost around October 1, giving about 144 frost-free days a year.
- Hardiness zone
- Zone 4a
- Typical last frost
- May 10
- Typical first frost
- October 1
- Frost-free season
- 144 days
Frost dates in Grand Forks
Last spring frost
- April 28Risky: frost later than this in 9 years out of 10
- May 10Typical: a later frost in half of years
- May 24Safe: a later frost only 1 year in 10
First fall frost
- September 20Risky: frost earlier than this 1 year in 10
- October 1Typical: an earlier frost in half of years
- October 15Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 144 days. Frost here means a low of 32°F at the weather station. A hard freeze (28°F), which damages most hardy crops too, typically ends around April 30 and returns around October 12.
NOAA U.S. Climate Normals 1991-2020 for Grand Forks Univ (Nws), 3 miles W of the city center. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers.
What to plant each month in Grand Forks
January
Start indoors: onions
February
Start indoors: broccoli, cauliflower, collard greens, kale, leeks, onions, petunias, ranunculus
March
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, kale, leeks, lettuce, marigolds, nasturtiums, onions, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons, spinach, swiss chard
Plant or sow outdoors: black-eyed susans, blueberries, garlic, grapes, grass seed, hollyhocks, onions, peas, poppies, raspberries, rhubarb, strawberries, turnips, wildflowers
April
Start indoors: basil, cantaloupes, celery, cilantro, eggplants, marigolds, nasturtiums, peppers, ranunculus, spinach, swiss chard, tomatoes, watermelons, zinnias
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, dahlias, dill, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, lettuce, onions, parsley, peas, poppies, radishes, ranunculus, raspberries, rhubarb, roses, snapdragons, spinach, strawberries, swiss chard, turnips, wildflowers
May
Start indoors: cantaloupes, cosmos, cucumbers, okra, pumpkins, watermelons, winter squash, zucchini
Plant or sow outdoors: asparagus, basil, beets, cantaloupes, carrots, cauliflower, chives, cilantro, cucumbers, dahlias, dill, eggplants, figs, garden mums, ginger, gladioli, grapes, green beans, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, oregano, parsley, peppers, perennial ryegrass, petunias, potatoes, pumpkins, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme, tomatoes, watermelons, winter squash, zinnias, zucchini
June
Plant or sow outdoors: asparagus, basil, bermudagrass, cantaloupes, celery, centipedegrass, cosmos, cucumbers, eggplants, garden mums, green beans, green onions, okra, peanuts, peppers, pumpkins, st. augustinegrass, sweet potatoes, tomatoes, watermelons, winter squash, zoysiagrass, zucchini
Plant for fall: brussels sprouts
July
Plant or sow outdoors: bermudagrass, centipedegrass, green onions, okra, st. augustinegrass, zoysiagrass
Plant for fall: bearded irises, beets, broccoli, brussels sprouts, cabbages, carrots, cauliflower, collard greens, daylilies, kale, lettuce, peas, radishes, snapdragons, spinach, swiss chard, turnips
August
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hydrangeas, kale, lettuce, lilies, ornamental alliums, peonies, radishes, roses, saffron, snapdragons, spinach, tulips, turnips
September
Plant for fall: crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, kale, lilies, ornamental alliums, peonies, radishes, saffron, tulips
October
Plant for fall: crocuses, daffodils, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
Frost dates and zones by ZIP code in Grand Forks
All 2 of Grand Forks's main ZIP codes take their frost dates from Grand Forks Univ (Nws), so the dates on this page apply across the city. Every one of them is in zone 4a.
Planting dates for popular crops in Grand Forks
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Apr 3 to 17 | May 29 to Jun 12 | — |
| Strawberries | — | Mar 29 to Apr 12 | — |
| Lettuce | Mar 15 to 29 | May 3 to 17 | Jul 2 to Aug 6 |
| Cilantro | Mar 29 to Apr 12 | May 10 to 17 | — |
| Basil | Apr 10 to 24 | May 29 to Jun 5 | — |
| Potatoes | — | May 5 to 12 | — |
| Garlic | — | Mar 29 to Apr 12 | Oct 1 to 15 |
| Onions | Jan 18 to Mar 1 | Apr 12 to 26 | — |
| Cucumbers | May 1 to 15 | May 29 to Jun 12 | — |
| Pumpkins | May 1 to 15 | May 29 to Jun 12 | — |
| Peppers | Mar 13 to Apr 10 | May 29 to Jun 12 | — |
| Carrots | — | Apr 19 to May 10 | Jul 9 to 30 |
| Sweet Potatoes | — | Jun 13 to 20 | — |
| Watermelons | Apr 24 to May 8 | May 29 to Jun 12 | — |
| Sweet Corn | — | May 10 to 24 | — |
| Green Beans | — | May 29 to Jun 12 | — |
| Zucchini | May 1 to 15 | May 29 to Jun 12 | — |
| Broccoli | Feb 22 to Mar 15 | Apr 12 to 26 | Jul 16 to Aug 13 |
| Peas | — | Mar 29 to Apr 12 | Jul 9 to 23 |
| Spinach | Mar 29 to Apr 5 | May 3 to 17 | Jul 23 to Aug 27 |
| Sunflowers | — | May 10 to 31 | — |
| Zinnias | Apr 12 to 19 | May 10 to 24 | — |
| Tulips | — | — | Aug 20 to Oct 15 |
| Daffodils | — | — | Aug 20 to Oct 1 |
| Grass Seed | — | Mar 29 to Apr 12 | Aug 20 to Sep 3 |
Nearby cities
- Fargo, ND zone 4a, last frost May 10
- Bismarck, ND zone 4a, last frost May 14
- St. Cloud, MN zone 4b, last frost May 7
- Duluth, MN zone 4b, last frost May 6
- Maple Grove, MN zone 5a, last frost Apr 30
- Coon Rapids, MN zone 5a, last frost Apr 30
Planting in North DakotaAbout zone 4aPrintable calendar for Grand Forks
Questions
When is the last frost in Grand Forks?
Around May 10 in a typical year, based on NOAA's 1991-2020 records for Grand Forks Univ (Nws). There is still a 1 in 10 chance of frost after May 24.
What planting zone is Grand Forks in?
USDA hardiness zone 4a (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Grand Forks?
Start seeds indoors April 3 to 17 and set plants out May 29 to June 12.
When is the first frost in Grand Forks?
Around October 1 in a typical year, and before September 20 about 1 year in 10.