Bismarck, North Dakota frost dates
Frost risk by date
| Chance of frost | Spring: frost after | Fall: frost before |
|---|---|---|
| 90% | May 1 | October 9 |
| 70% | May 8 | October 2 |
| 50% | May 14 | September 27 |
| 30% | May 19 | September 23 |
| 10% | May 27 | September 15 |
Read the spring column like this: there is a 10% chance of a 32°F freeze after May 27. These are NOAA probabilities for the Bismarck weather station (USW00024011, elevation 505 m), 1991–2020.
Bismarck vegetable planting calendar
Dates count from the 50% last-frost date (May 14). For tomatoes, peppers and other frost-tender crops, waiting until the 10% date (May 27) is the cautious choice.
| Crop | Start seeds indoors | Plant out |
|---|---|---|
| Beans | Apr 23 | May 21 (usually sown directly in the garden) |
| Broccoli | Mar 5 | Apr 16 |
| Brussels sprouts | Mar 5 | Apr 16 |
| Cabbage | Feb 26 | Apr 9 |
| Cauliflower | Mar 19 | Apr 30 |
| Sweet corn | Apr 16 | May 14 (usually sown directly in the garden) |
| Cucumbers | Apr 30 | May 21 |
| Kale | Feb 26 | Apr 9 |
| Leeks | Jan 29 | Apr 9 |
| Lettuce | Mar 26 | Apr 30 |
| Melons | May 7 | May 28 |
| Onions | Jan 22 | Apr 2 (from seed; sets and transplants go out at the same time) |
| Peas | Mar 19 | Apr 16 (usually sown directly in the garden) |
| Peppers | Apr 2 | May 28 |
| Squash | May 7 | May 28 |
| Tomatoes | Mar 19 | May 14 |
Offsets from Oregon State University Extension's seed-starting table. "Plant out" means transplant, or sow directly for crops usually grown from seed.
Fall frost and season extension
The first fall freeze usually arrives around September 27. There's a 1-in-10 chance it comes before September 15. Harvest tender crops such as basil, tomatoes, peppers and squash before then, or cover them on cold nights. Cool-season crops like kale, cabbage and Brussels sprouts handle light frost, and often taste sweeter after it. A hard freeze (28°F) typically comes around October 5.
Nearby cities
| City | Last frost (50%) | First frost (50%) | Distance |
|---|---|---|---|
| Fargo, ND | May 10 | Sep 30 | ~301 km |
| Rapid City, SD | May 12 | Oct 1 | ~349 km |
| Sioux Falls, SD | May 1 | Oct 6 | ~468 km |
| Billings, MT | May 4 | Oct 7 | ~601 km |
| Minneapolis, MN | Apr 23 | Oct 18 | ~610 km |
| Duluth, MN | May 13 | Oct 1 | ~650 km |