When to Plant Onions in South Dakota
In a typical South Dakota location, start seeds indoors Feb 25 – Mar 11, then transplant outdoors Apr 8 – Apr 22. Across the state, the outdoor planting window starts as early as Mar 29 in Tea and as late as Apr 14 in Ellsworth Air Force Base.
Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.
Onions Planting Dates by City
| City | Start indoors | Transplant |
|---|---|---|
| Sioux Falls | Feb 20 – Mar 6 | Apr 3 – Apr 17 |
| Rapid City | Feb 22 – Mar 8 | Apr 5 – Apr 19 |
| Aberdeen | Feb 27 – Mar 13 | Apr 10 – Apr 24 |
| Brookings | Feb 25 – Mar 11 | Apr 8 – Apr 22 |
| Watertown | Feb 26 – Mar 12 | Apr 9 – Apr 23 |
| Mitchell | Feb 21 – Mar 7 | Apr 4 – Apr 18 |
| Yankton | Feb 16 – Mar 2 | Mar 30 – Apr 13 |
| Pierre | Feb 25 – Mar 11 | Apr 8 – Apr 22 |
| Huron | Feb 25 – Mar 11 | Apr 8 – Apr 22 |
| Spearfish | Mar 3 – Mar 17 | Apr 14 – Apr 28 |
| Vermillion | Feb 22 – Mar 8 | Apr 5 – Apr 19 |
| Brandon | Feb 20 – Mar 6 | Apr 3 – Apr 17 |
| Box Elder | Mar 3 – Mar 17 | Apr 14 – Apr 28 |
| Rapid Valley | Feb 22 – Mar 8 | Apr 5 – Apr 19 |
| Ellsworth Air Force Base | Mar 3 – Mar 17 | Apr 14 – Apr 28 |
| Madison | Feb 24 – Mar 10 | Apr 7 – Apr 21 |
| Sturgis | Feb 27 – Mar 13 | Apr 10 – Apr 24 |
| Belle Fourche | Mar 1 – Mar 15 | Apr 12 – Apr 26 |
| Harrisburg | Feb 21 – Mar 7 | Apr 4 – Apr 18 |
| Tea | Feb 15 – Mar 1 | Mar 29 – Apr 12 |
Showing the 20 most populous of 20 South Dakota cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all South Dakota cities.
Frequently Asked Questions
When should I plant onions in South Dakota?
In a typical South Dakota location, start seeds indoors Feb 25 – Mar 11, then transplant outdoors Apr 8 – Apr 22. Across the state, the outdoor planting window starts as early as Mar 29 in Tea and as late as Apr 14 in Ellsworth Air Force Base.
When is the last frost in South Dakota?
The average last spring frost in South Dakota ranges from April 26 in Tea to May 12 in Ellsworth Air Force Base, based on NOAA 1991–2020 climate normals.
How long do onions take to grow?
Onions typically take 90–120 days from planting to harvest. Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.
Other Crops in South Dakota
- Tomatoes
- Peppers
- Eggplant
- Cucumbers
- Zucchini
- Winter Squash
- Pumpkins
- Watermelon
- Cantaloupe
- Corn
- Green Beans
- Peas
- Lettuce
- Spinach
- Kale
- Arugula
- Swiss Chard
- Broccoli
- Cauliflower
- Cabbage
- Brussels Sprouts
- Carrots
- Beets
- Radishes
- Turnips
- Garlic
- Potatoes
- Sweet Potatoes
- Asparagus
- Basil
- Cilantro
- Parsley
- Dill
- Oregano
- Thyme
- Sunflowers
- Zinnias
- Marigolds
- Cosmos
- Nasturtiums
- Dahlias
When to plant onions in other states