Hillsboro, ND frost dates
Last spring frostMay 2median date
First fall frostOct 9median date
Growing season160 daysfrost-free
Hardiness zone4aZone 4a
How Hillsboro compares
- In 8 years out of 10, the last spring frost in Hillsboro falls between April 15 and May 17, a 32-day window. The first fall frost falls between September 25 and October 25.
- The median last frost is 10 days earlier than the North Dakota median of May 12.
- Its 160-day growing season is among the longest of the 372 North Dakota places with a regular frost season.
- The last frost is 10 days earlier than the zone 4a median of May 12. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4a chart.
- The weather station records an average of 174 nights a year at or below 32°F.
- Compared with Grand Forks, ND, 60 km away, the last frost here is 8 days earlier than there and the growing season is 16 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 15 |
| 50% (median) | May 2 |
| 10% (safe for tender plants) | May 17 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 25 |
| 50% (median) | October 9 |
| 90% (late) | October 25 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Hillsboro, ND
Hillsboro, ND frost dates — last frost May 2, first frost Oct 9, zone 4a. whenisthelastfrost.com
Crop
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Start indoors: Feb 7 to Feb 21Transplant outside: Apr 4 to Apr 18
Start indoors: Feb 21 to Mar 7Transplant outside: May 16 to May 30
Start indoors: Feb 21 to Mar 7Transplant outside: May 16 to May 30
Start indoors: Mar 7 to Mar 21Transplant outside: May 9 to May 23
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Sow outdoors: Apr 4 to May 9Plant for fall: Aug 14 to Sep 11
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 4 to Apr 18Sow outdoors: Apr 4 to Apr 18Plant for fall: Jul 31 to Aug 21
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 21 to Apr 4Transplant outside: May 23 to Jun 6Sow outdoors: May 23 to Jun 6
Start indoors: Mar 21 to Apr 4Transplant outside: May 9 to May 23
Sow outdoors: Mar 21 to Apr 11Plant for fall: Jul 17 to Aug 7
Sow outdoors: Mar 21 to Apr 11Plant for fall: Aug 14 to Sep 4
Sow outdoors: Mar 28 to May 9Plant for fall: Aug 28 to Sep 18
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 23Sow outdoors: May 9 to May 23Plant for fall: Jul 24 to Aug 7
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23Plant for fall: Jul 31 to Aug 14
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 30
Sow outdoors: Apr 11 to May 9Plant for fall: Jul 17 to Jul 31
Sow outdoors: Apr 11 to May 9Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 11 to May 2
Sow outdoors: Apr 18 to May 16Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 18 to May 9Plant for fall: Aug 14 to Sep 4
Sow outdoors: May 9 to May 30Plant for fall: Jul 24 to Aug 7
Sow outdoors: May 9 to May 23
Transplant outside: May 16 to Jun 6
Plant for fall: Sep 25 to Oct 30
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hillsboro, ND
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 7 – Feb 21 | Apr 4 – Apr 18 | — | — |
| Peppers | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Eggplant | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Tomatoes | Mar 7 – Mar 21 | May 9 – May 23 | — | — |
| Lettuce | Mar 7 – Mar 21 | Apr 11 – Apr 25 | Apr 4 – May 9 | Aug 14 – Sep 11 |
| Kale | Mar 7 – Mar 21 | Apr 4 – Apr 18 | Apr 4 – Apr 18 | Jul 31 – Aug 21 |
| Broccoli | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jul 3 – Jul 24 |
| Cabbage | Mar 7 – Mar 21 | Apr 11 – Apr 25 | — | Jul 3 – Jul 24 |
| Cauliflower | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jul 3 – Jul 24 |
| Okra | Mar 21 – Apr 4 | May 23 – Jun 6 | May 23 – Jun 6 | — |
| Basil | Mar 21 – Apr 4 | May 9 – May 23 | — | — |
| Peas | — | — | Mar 21 – Apr 11 | Jul 17 – Aug 7 |
| Spinach | — | — | Mar 21 – Apr 11 | Aug 14 – Sep 4 |
| Radishes | — | — | Mar 28 – May 9 | Aug 28 – Sep 18 |
| Cucumbers | Apr 4 – Apr 11 | May 16 – May 23 | May 9 – May 23 | Jul 24 – Aug 7 |
| Zucchini & Summer Squash | Apr 4 – Apr 11 | — | May 9 – May 23 | Jul 31 – Aug 14 |
| Winter Squash & Pumpkins | Apr 4 – Apr 11 | — | May 9 – May 23 | — |
| Melons & Watermelon | Apr 4 – Apr 11 | May 16 – May 30 | — | — |
| Carrots | — | — | Apr 11 – May 9 | Jul 17 – Jul 31 |
| Beets | — | — | Apr 11 – May 9 | Jul 31 – Aug 14 |
| Potatoes | — | — | Apr 11 – May 2 | — |
| Swiss Chard | — | — | Apr 18 – May 16 | Jul 31 – Aug 14 |
| Cilantro | — | — | Apr 18 – May 9 | Aug 14 – Sep 4 |
| Green Beans | — | — | May 9 – May 30 | Jul 24 – Aug 7 |
| Sweet Corn | — | — | May 9 – May 23 | — |
| Sweet Potatoes | — | May 16 – Jun 6 | — | — |
| Garlic | — | — | — | Sep 25 – Oct 30 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Hillsboro 3 N, ND weather station, 6 km away (elevation 909 ft (277 m)).
Frost dates near Hillsboro
- Blanchard May 2 · Oct 9
- Caledonia May 2 · Oct 9
- Cummings May 2 · Oct 9
- Grandin May 9 · Oct 1
- Mayville May 13 · Sep 27
- Hunter May 2 · Oct 9
- Buxton May 2 · Oct 9
- Clifford May 13 · Sep 27
- Portland May 13 · Sep 27
- Galesburg May 10 · Sep 24
Frequently asked questions
When is the last frost in Hillsboro, ND?
The median last spring frost in Hillsboro, ND is May 2. There is still about a 10% chance of frost after May 17, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hillsboro, ND?
The median first fall frost is October 9, with about a 10% chance of frost before September 25.
How long is the growing season in Hillsboro, ND?
About 160 days between the median last spring frost and first fall frost.
What planting zone is Hillsboro, ND?
Hillsboro, ND is in USDA hardiness zone 4a.