Seneca, SD frost dates
Last spring frostMay 14median date
First fall frostSep 29median date
Growing season138 daysfrost-free
Hardiness zone4bZone 4b
How Seneca compares
- In 8 years out of 10, the last spring frost in Seneca falls between April 30 and May 25, a 25-day window. The first fall frost falls between September 16 and October 12.
- The median last frost is 8 days later than the South Dakota median of May 6.
- Its 138-day growing season is longer than 10% of the 363 South Dakota places with a regular frost season (state median 149 days).
- The last frost is 6 days later 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 177 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 30 |
| 50% (median) | May 14 |
| 10% (safe for tender plants) | May 25 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 16 |
| 50% (median) | September 29 |
| 90% (late) | October 12 |
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 Seneca, SD
Seneca, SD frost dates — last frost May 14, first frost Sep 29, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Feb 19 to Mar 5Transplant outside: Apr 16 to Apr 30
Start indoors: Mar 5 to Mar 19Transplant outside: May 28 to Jun 11
Start indoors: Mar 5 to Mar 19Transplant outside: May 28 to Jun 11
Start indoors: Mar 19 to Apr 2Transplant outside: May 21 to Jun 4
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 23 to May 7Sow outdoors: Apr 16 to May 21Plant for fall: Aug 4 to Sep 1
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 16 to Apr 30Sow outdoors: Apr 16 to Apr 30Plant for fall: Jul 21 to Aug 11
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 30 to May 14Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 23 to May 7Plant for fall: Jun 23 to Jul 14
Start indoors: Mar 19 to Apr 2Transplant outside: Apr 30 to May 14Plant for fall: Jun 23 to Jul 14
Start indoors: Apr 2 to Apr 16Transplant outside: Jun 4 to Jun 18Sow outdoors: Jun 4 to Jun 18
Start indoors: Apr 2 to Apr 16Transplant outside: May 21 to Jun 4
Sow outdoors: Apr 2 to Apr 23Plant for fall: Jul 7 to Jul 28
Sow outdoors: Apr 2 to Apr 23Plant for fall: Aug 4 to Aug 25
Sow outdoors: Apr 9 to May 21Plant for fall: Aug 18 to Sep 8
Start indoors: Apr 16 to Apr 23Transplant outside: May 28 to Jun 4Sow outdoors: May 21 to Jun 4Plant for fall: Jul 14 to Jul 28
Start indoors: Apr 16 to Apr 23Sow outdoors: May 21 to Jun 4Plant for fall: Jul 21 to Aug 4
Start indoors: Apr 16 to Apr 23Sow outdoors: May 21 to Jun 4
Start indoors: Apr 16 to Apr 23Transplant outside: May 28 to Jun 11
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 7 to Jul 21
Sow outdoors: Apr 23 to May 21Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 23 to May 14
Sow outdoors: Apr 30 to May 28Plant for fall: Jul 21 to Aug 4
Sow outdoors: Apr 30 to May 21Plant for fall: Aug 4 to Aug 25
Sow outdoors: May 21 to Jun 11Plant for fall: Jul 14 to Jul 28
Sow outdoors: May 21 to Jun 4
Transplant outside: May 28 to Jun 18
Plant for fall: Sep 15 to Oct 20
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Seneca, SD
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 19 – Mar 5 | Apr 16 – Apr 30 | — | — |
| Peppers | Mar 5 – Mar 19 | May 28 – Jun 11 | — | — |
| Eggplant | Mar 5 – Mar 19 | May 28 – Jun 11 | — | — |
| Tomatoes | Mar 19 – Apr 2 | May 21 – Jun 4 | — | — |
| Lettuce | Mar 19 – Apr 2 | Apr 23 – May 7 | Apr 16 – May 21 | Aug 4 – Sep 1 |
| Kale | Mar 19 – Apr 2 | Apr 16 – Apr 30 | Apr 16 – Apr 30 | Jul 21 – Aug 11 |
| Broccoli | Mar 19 – Apr 2 | Apr 30 – May 14 | — | Jun 23 – Jul 14 |
| Cabbage | Mar 19 – Apr 2 | Apr 23 – May 7 | — | Jun 23 – Jul 14 |
| Cauliflower | Mar 19 – Apr 2 | Apr 30 – May 14 | — | Jun 23 – Jul 14 |
| Okra | Apr 2 – Apr 16 | Jun 4 – Jun 18 | Jun 4 – Jun 18 | — |
| Basil | Apr 2 – Apr 16 | May 21 – Jun 4 | — | — |
| Peas | — | — | Apr 2 – Apr 23 | Jul 7 – Jul 28 |
| Spinach | — | — | Apr 2 – Apr 23 | Aug 4 – Aug 25 |
| Radishes | — | — | Apr 9 – May 21 | Aug 18 – Sep 8 |
| Cucumbers | Apr 16 – Apr 23 | May 28 – Jun 4 | May 21 – Jun 4 | Jul 14 – Jul 28 |
| Zucchini & Summer Squash | Apr 16 – Apr 23 | — | May 21 – Jun 4 | Jul 21 – Aug 4 |
| Winter Squash & Pumpkins | Apr 16 – Apr 23 | — | May 21 – Jun 4 | — |
| Melons & Watermelon | Apr 16 – Apr 23 | May 28 – Jun 11 | — | — |
| Carrots | — | — | Apr 23 – May 21 | Jul 7 – Jul 21 |
| Beets | — | — | Apr 23 – May 21 | Jul 21 – Aug 4 |
| Potatoes | — | — | Apr 23 – May 14 | — |
| Swiss Chard | — | — | Apr 30 – May 28 | Jul 21 – Aug 4 |
| Cilantro | — | — | Apr 30 – May 21 | Aug 4 – Aug 25 |
| Green Beans | — | — | May 21 – Jun 11 | Jul 14 – Jul 28 |
| Sweet Corn | — | — | May 21 – Jun 4 | — |
| Sweet Potatoes | — | May 28 – Jun 18 | — | — |
| Garlic | — | — | — | Sep 15 – Oct 20 |
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 Highmore 23 N, SD weather station, 20 km away (elevation 1,870 ft (570 m)).
Frost dates near Seneca
- Onaka May 7 · Oct 3
- Tolstoy May 7 · Oct 2
- Lebanon May 7 · Oct 2
- Faulkton May 10 · Sep 28
- Hoven May 7 · Oct 2
- Orient May 10 · Sep 28
- Gettysburg May 7 · Oct 2
- Cresbard May 10 · Sep 28
- Roscoe May 7 · Oct 3
- Rockham May 8 · Oct 1
Frequently asked questions
When is the last frost in Seneca, SD?
The median last spring frost in Seneca, SD is May 14. There is still about a 10% chance of frost after May 25, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Seneca, SD?
The median first fall frost is September 29, with about a 10% chance of frost before September 16.
How long is the growing season in Seneca, SD?
About 138 days between the median last spring frost and first fall frost.
What planting zone is Seneca, SD?
Seneca, SD is in USDA hardiness zone 4b.