When to plant onions in South Dakota

Plant out in Sioux Falls

Mar 15–Apr 5

Across South Dakota the window opens between March 15 and March 27. Find your city below; the dates follow each town's own average last frost.

Start indoors, Sioux Falls: Feb 1–Mar 1
Plant out, Sioux Falls: Mar 15–Apr 5
Last frost, Sioux Falls: Apr 26

Start seeds indoors 8–12 weeks before the last frost; plant out 3–6 weeks before the last frost. Northern gardens need long-day varieties and southern gardens need short-day ones. A wrong pick gives small bulbs.

Onions planting dates by city

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost

JanFebMarAprMayJunJulAugSepOctNovDec

Sioux FallsMar 15–Apr 5

Rapid CityMar 22–Apr 12

AberdeenMar 27–Apr 17

BrookingsMar 25–Apr 15

WatertownMar 26–Apr 16

Questions

When should I plant onions in South Dakota?

In Sioux Falls, plant out from March 15 to April 5. Across South Dakota the window opens between March 15 and March 27, depending on the local last frost.

How is this date worked out?

Start seeds indoors 8–12 weeks before the last frost; plant out 3–6 weeks before the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.

More for South Dakota

Onions in other states

Frost dates for every city in South Dakota