Twin Brooks, SD frost dates
Last spring frostMay 2median date
First fall frostOct 4median date
Growing season155 daysfrost-free
Hardiness zone4bZone 4b
How Twin Brooks compares
- In 8 years out of 10, the last spring frost in Twin Brooks falls between April 20 and May 15, a 25-day window. The first fall frost falls between September 22 and October 16.
- The median last frost is 4 days earlier than the South Dakota median of May 6.
- Its 155-day growing season is longer than 73% of the 363 South Dakota places with a regular frost season (state median 149 days).
- The last frost is 6 days earlier than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 174 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 20 |
| 50% (median) | May 2 |
| 10% (safe for tender plants) | May 15 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 22 |
| 50% (median) | October 4 |
| 90% (late) | October 16 |
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 Twin Brooks, SD
Twin Brooks, SD frost dates — last frost May 2, first frost Oct 4, zone 4b. 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 9 to Sep 6
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 4 to Apr 18Sow outdoors: Apr 4 to Apr 18Plant for fall: Jul 26 to Aug 16
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jun 28 to Jul 19
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Plant for fall: Jun 28 to Jul 19
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jun 28 to Jul 19
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 12 to Aug 2
Sow outdoors: Mar 21 to Apr 11Plant for fall: Aug 9 to Aug 30
Sow outdoors: Mar 28 to May 9Plant for fall: Aug 23 to Sep 13
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 23Sow outdoors: May 9 to May 23Plant for fall: Jul 19 to Aug 2
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23Plant for fall: Jul 26 to Aug 9
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 12 to Jul 26
Sow outdoors: Apr 11 to May 9Plant for fall: Jul 26 to Aug 9
Sow outdoors: Apr 11 to May 2
Sow outdoors: Apr 18 to May 16Plant for fall: Jul 26 to Aug 9
Sow outdoors: Apr 18 to May 9Plant for fall: Aug 9 to Aug 30
Sow outdoors: May 9 to May 30Plant for fall: Jul 19 to Aug 2
Sow outdoors: May 9 to May 23
Transplant outside: May 16 to Jun 6
Plant for fall: Sep 20 to Oct 25
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Twin Brooks, SD
| 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 9 – Sep 6 |
| Kale | Mar 7 – Mar 21 | Apr 4 – Apr 18 | Apr 4 – Apr 18 | Jul 26 – Aug 16 |
| Broccoli | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jun 28 – Jul 19 |
| Cabbage | Mar 7 – Mar 21 | Apr 11 – Apr 25 | — | Jun 28 – Jul 19 |
| Cauliflower | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jun 28 – Jul 19 |
| 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 12 – Aug 2 |
| Spinach | — | — | Mar 21 – Apr 11 | Aug 9 – Aug 30 |
| Radishes | — | — | Mar 28 – May 9 | Aug 23 – Sep 13 |
| Cucumbers | Apr 4 – Apr 11 | May 16 – May 23 | May 9 – May 23 | Jul 19 – Aug 2 |
| Zucchini & Summer Squash | Apr 4 – Apr 11 | — | May 9 – May 23 | Jul 26 – Aug 9 |
| 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 12 – Jul 26 |
| Beets | — | — | Apr 11 – May 9 | Jul 26 – Aug 9 |
| Potatoes | — | — | Apr 11 – May 2 | — |
| Swiss Chard | — | — | Apr 18 – May 16 | Jul 26 – Aug 9 |
| Cilantro | — | — | Apr 18 – May 9 | Aug 9 – Aug 30 |
| Green Beans | — | — | May 9 – May 30 | Jul 19 – Aug 2 |
| Sweet Corn | — | — | May 9 – May 23 | — |
| Sweet Potatoes | — | May 16 – Jun 6 | — | — |
| Garlic | — | — | — | Sep 20 – Oct 25 |
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 Milbank 4 Nw, SD weather station, 13 km away (elevation 1,145 ft (349 m)).
Frost dates near Twin Brooks
- Marvin May 14 · Sep 28
- Stockholm May 5 · Oct 2
- Milbank May 5 · Oct 2
- Corona May 2 · Oct 4
- South Shore May 7 · Sep 28
- Wilmot May 5 · Oct 1
- Big Stone City May 5 · Oct 2
- Strandburg May 5 · Oct 2
- Summit May 14 · Sep 28
- Labolt May 5 · Oct 2
Frequently asked questions
When is the last frost in Twin Brooks, SD?
The median last spring frost in Twin Brooks, SD is May 2. There is still about a 10% chance of frost after May 15, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Twin Brooks, SD?
The median first fall frost is October 4, with about a 10% chance of frost before September 22.
How long is the growing season in Twin Brooks, SD?
About 155 days between the median last spring frost and first fall frost.
What planting zone is Twin Brooks, SD?
Twin Brooks, SD is in USDA hardiness zone 4b.