Castlewood, SD frost dates
Last spring frostMay 10median date
First fall frostSep 27median date
Growing season140 daysfrost-free
Hardiness zone4aZone 4a
How Castlewood compares
- In 8 years out of 10, the last spring frost in Castlewood falls between April 29 and May 23, a 24-day window. The first fall frost falls between September 14 and October 7.
- The median last frost is 4 days later than the South Dakota median of May 6.
- Its 140-day growing season is longer than 13% of the 363 South Dakota places with a regular frost season (state median 149 days).
- The last frost is typical for zone 4a, where the median is May 12.
- The weather station records an average of 187 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 29 |
| 50% (median) | May 10 |
| 10% (safe for tender plants) | May 23 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 14 |
| 50% (median) | September 27 |
| 90% (late) | October 7 |
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 Castlewood, SD
Castlewood, SD frost dates — last frost May 10, first frost Sep 27, zone 4a. whenisthelastfrost.com
Crop
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Start indoors: Feb 15 to Mar 1Transplant outside: Apr 12 to Apr 26
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 1 to Mar 15Transplant outside: May 24 to Jun 7
Start indoors: Mar 15 to Mar 29Transplant outside: May 17 to May 31
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Sow outdoors: Apr 12 to May 17Plant for fall: Aug 2 to Aug 30
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 12 to Apr 26Sow outdoors: Apr 12 to Apr 26Plant for fall: Jul 19 to Aug 9
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 21 to Jul 12
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 19 to May 3Plant for fall: Jun 21 to Jul 12
Start indoors: Mar 15 to Mar 29Transplant outside: Apr 26 to May 10Plant for fall: Jun 21 to Jul 12
Start indoors: Mar 29 to Apr 12Transplant outside: May 31 to Jun 14Sow outdoors: May 31 to Jun 14
Start indoors: Mar 29 to Apr 12Transplant outside: May 17 to May 31
Sow outdoors: Mar 29 to Apr 19Plant for fall: Jul 5 to Jul 26
Sow outdoors: Mar 29 to Apr 19Plant for fall: Aug 2 to Aug 23
Sow outdoors: Apr 5 to May 17Plant for fall: Aug 16 to Sep 6
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to May 31Sow outdoors: May 17 to May 31Plant for fall: Jul 12 to Jul 26
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31Plant for fall: Jul 19 to Aug 2
Start indoors: Apr 12 to Apr 19Sow outdoors: May 17 to May 31
Start indoors: Apr 12 to Apr 19Transplant outside: May 24 to Jun 7
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 5 to Jul 19
Sow outdoors: Apr 19 to May 17Plant for fall: Jul 19 to Aug 2
Sow outdoors: Apr 19 to May 10
Sow outdoors: Apr 26 to May 24Plant for fall: Jul 19 to Aug 2
Sow outdoors: Apr 26 to May 17Plant for fall: Aug 2 to Aug 23
Sow outdoors: May 17 to Jun 7Plant for fall: Jul 12 to Jul 26
Sow outdoors: May 17 to May 31
Transplant outside: May 24 to Jun 14
Plant for fall: Sep 13 to Oct 18
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Castlewood, SD
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 15 – Mar 1 | Apr 12 – Apr 26 | — | — |
| Peppers | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Eggplant | Mar 1 – Mar 15 | May 24 – Jun 7 | — | — |
| Tomatoes | Mar 15 – Mar 29 | May 17 – May 31 | — | — |
| Lettuce | Mar 15 – Mar 29 | Apr 19 – May 3 | Apr 12 – May 17 | Aug 2 – Aug 30 |
| Kale | Mar 15 – Mar 29 | Apr 12 – Apr 26 | Apr 12 – Apr 26 | Jul 19 – Aug 9 |
| Broccoli | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 21 – Jul 12 |
| Cabbage | Mar 15 – Mar 29 | Apr 19 – May 3 | — | Jun 21 – Jul 12 |
| Cauliflower | Mar 15 – Mar 29 | Apr 26 – May 10 | — | Jun 21 – Jul 12 |
| Okra | Mar 29 – Apr 12 | May 31 – Jun 14 | May 31 – Jun 14 | — |
| Basil | Mar 29 – Apr 12 | May 17 – May 31 | — | — |
| Peas | — | — | Mar 29 – Apr 19 | Jul 5 – Jul 26 |
| Spinach | — | — | Mar 29 – Apr 19 | Aug 2 – Aug 23 |
| Radishes | — | — | Apr 5 – May 17 | Aug 16 – Sep 6 |
| Cucumbers | Apr 12 – Apr 19 | May 24 – May 31 | May 17 – May 31 | Jul 12 – Jul 26 |
| Zucchini & Summer Squash | Apr 12 – Apr 19 | — | May 17 – May 31 | Jul 19 – Aug 2 |
| Winter Squash & Pumpkins | Apr 12 – Apr 19 | — | May 17 – May 31 | — |
| Melons & Watermelon | Apr 12 – Apr 19 | May 24 – Jun 7 | — | — |
| Carrots | — | — | Apr 19 – May 17 | Jul 5 – Jul 19 |
| Beets | — | — | Apr 19 – May 17 | Jul 19 – Aug 2 |
| Potatoes | — | — | Apr 19 – May 10 | — |
| Swiss Chard | — | — | Apr 26 – May 24 | Jul 19 – Aug 2 |
| Cilantro | — | — | Apr 26 – May 17 | Aug 2 – Aug 23 |
| Green Beans | — | — | May 17 – Jun 7 | Jul 12 – Jul 26 |
| Sweet Corn | — | — | May 17 – May 31 | — |
| Sweet Potatoes | — | May 24 – Jun 14 | — | — |
| Garlic | — | — | — | Sep 13 – Oct 18 |
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 Castlewood, SD weather station, about 1 km away (elevation 1,686 ft (514 m)).
Frost dates near Castlewood
- Estelline May 10 · Sep 27
- Hayti May 6 · Oct 1
- Kranzburg May 3 · Oct 4
- Goodwin May 7 · Oct 1
- Watertown May 7 · Sep 30
- Lake Norden May 6 · Oct 1
- Hazel May 3 · Oct 4
- Clear Lake May 7 · Oct 1
- Toronto May 6 · Oct 3
- Brandt May 7 · Oct 1
Frequently asked questions
When is the last frost in Castlewood, SD?
The median last spring frost in Castlewood, SD is May 10. There is still about a 10% chance of frost after May 23, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Castlewood, SD?
The median first fall frost is September 27, with about a 10% chance of frost before September 14.
How long is the growing season in Castlewood, SD?
About 140 days between the median last spring frost and first fall frost.
What planting zone is Castlewood, SD?
Castlewood, SD is in USDA hardiness zone 4a.