Watertown, SD frost dates
Last spring frostMay 7median date
First fall frostSep 30median date
Growing season146 daysfrost-free
Hardiness zone4bZone 4b
How Watertown compares
- In 8 years out of 10, the last spring frost in Watertown falls between April 26 and May 20, a 24-day window. The first fall frost falls between September 19 and October 13.
- The median last frost is 1 day later than the South Dakota median of May 6.
- Its 146-day growing season is longer than 35% of the 363 South Dakota places with a regular frost season (state median 149 days).
- The last frost is typical for zone 4b, where the median is May 8.
- 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 26 |
| 50% (median) | May 7 |
| 10% (safe for tender plants) | May 20 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 19 |
| 50% (median) | September 30 |
| 90% (late) | October 13 |
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 Watertown, SD
Watertown, SD frost dates — last frost May 7, first frost Sep 30, zone 4b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Feb 12 to Feb 26Transplant outside: Apr 9 to Apr 23
Start indoors: Feb 26 to Mar 12Transplant outside: May 21 to Jun 4
Start indoors: Feb 26 to Mar 12Transplant outside: May 21 to Jun 4
Start indoors: Mar 12 to Mar 26Transplant outside: May 14 to May 28
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 16 to Apr 30Sow outdoors: Apr 9 to May 14Plant for fall: Aug 5 to Sep 2
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 9 to Apr 23Sow outdoors: Apr 9 to Apr 23Plant for fall: Jul 22 to Aug 12
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 23 to May 7Plant for fall: Jun 24 to Jul 15
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 16 to Apr 30Plant for fall: Jun 24 to Jul 15
Start indoors: Mar 12 to Mar 26Transplant outside: Apr 23 to May 7Plant for fall: Jun 24 to Jul 15
Start indoors: Mar 26 to Apr 9Transplant outside: May 28 to Jun 11Sow outdoors: May 28 to Jun 11
Start indoors: Mar 26 to Apr 9Transplant outside: May 14 to May 28
Sow outdoors: Mar 26 to Apr 16Plant for fall: Jul 8 to Jul 29
Sow outdoors: Mar 26 to Apr 16Plant for fall: Aug 5 to Aug 26
Sow outdoors: Apr 2 to May 14Plant for fall: Aug 19 to Sep 9
Start indoors: Apr 9 to Apr 16Transplant outside: May 21 to May 28Sow outdoors: May 14 to May 28Plant for fall: Jul 15 to Jul 29
Start indoors: Apr 9 to Apr 16Sow outdoors: May 14 to May 28Plant for fall: Jul 22 to Aug 5
Start indoors: Apr 9 to Apr 16Sow outdoors: May 14 to May 28
Start indoors: Apr 9 to Apr 16Transplant outside: May 21 to Jun 4
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 8 to Jul 22
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 22 to Aug 5
Sow outdoors: Apr 16 to May 7
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 22 to Aug 5
Sow outdoors: Apr 23 to May 14Plant for fall: Aug 5 to Aug 26
Sow outdoors: May 14 to Jun 4Plant for fall: Jul 15 to Jul 29
Sow outdoors: May 14 to May 28
Transplant outside: May 21 to Jun 11
Plant for fall: Sep 16 to Oct 21
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Watertown, SD
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 12 – Feb 26 | Apr 9 – Apr 23 | — | — |
| Peppers | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Eggplant | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Tomatoes | Mar 12 – Mar 26 | May 14 – May 28 | — | — |
| Lettuce | Mar 12 – Mar 26 | Apr 16 – Apr 30 | Apr 9 – May 14 | Aug 5 – Sep 2 |
| Kale | Mar 12 – Mar 26 | Apr 9 – Apr 23 | Apr 9 – Apr 23 | Jul 22 – Aug 12 |
| Broccoli | Mar 12 – Mar 26 | Apr 23 – May 7 | — | Jun 24 – Jul 15 |
| Cabbage | Mar 12 – Mar 26 | Apr 16 – Apr 30 | — | Jun 24 – Jul 15 |
| Cauliflower | Mar 12 – Mar 26 | Apr 23 – May 7 | — | Jun 24 – Jul 15 |
| Okra | Mar 26 – Apr 9 | May 28 – Jun 11 | May 28 – Jun 11 | — |
| Basil | Mar 26 – Apr 9 | May 14 – May 28 | — | — |
| Peas | — | — | Mar 26 – Apr 16 | Jul 8 – Jul 29 |
| Spinach | — | — | Mar 26 – Apr 16 | Aug 5 – Aug 26 |
| Radishes | — | — | Apr 2 – May 14 | Aug 19 – Sep 9 |
| Cucumbers | Apr 9 – Apr 16 | May 21 – May 28 | May 14 – May 28 | Jul 15 – Jul 29 |
| Zucchini & Summer Squash | Apr 9 – Apr 16 | — | May 14 – May 28 | Jul 22 – Aug 5 |
| Winter Squash & Pumpkins | Apr 9 – Apr 16 | — | May 14 – May 28 | — |
| Melons & Watermelon | Apr 9 – Apr 16 | May 21 – Jun 4 | — | — |
| Carrots | — | — | Apr 16 – May 14 | Jul 8 – Jul 22 |
| Beets | — | — | Apr 16 – May 14 | Jul 22 – Aug 5 |
| Potatoes | — | — | Apr 16 – May 7 | — |
| Swiss Chard | — | — | Apr 23 – May 21 | Jul 22 – Aug 5 |
| Cilantro | — | — | Apr 23 – May 14 | Aug 5 – Aug 26 |
| Green Beans | — | — | May 14 – Jun 4 | Jul 15 – Jul 29 |
| Sweet Corn | — | — | May 14 – May 28 | — |
| Sweet Potatoes | — | May 21 – Jun 11 | — | — |
| Garlic | — | — | — | Sep 16 – Oct 21 |
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 Watertown Rgnl Ap, SD weather station, 2 km away (elevation 1,749 ft (533 m)).
Frost dates near Watertown
- Kranzburg May 3 · Oct 4
- Castlewood May 10 · Sep 27
- Goodwin May 7 · Oct 1
- Florence May 7 · Sep 28
- Hazel May 3 · Oct 4
- South Shore May 7 · Sep 28
- Henry May 5 · Oct 5
- Hayti May 6 · Oct 1
- Strandburg May 5 · Oct 2
- Wallace May 7 · Sep 28
Frequently asked questions
When is the last frost in Watertown, SD?
The median last spring frost in Watertown, SD is May 7. There is still about a 10% chance of frost after May 20, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Watertown, SD?
The median first fall frost is September 30, with about a 10% chance of frost before September 19.
How long is the growing season in Watertown, SD?
About 146 days between the median last spring frost and first fall frost.
What planting zone is Watertown, SD?
Watertown, SD is in USDA hardiness zone 4b.