Seed Starting Calendar for Kansas

Count back from the median last frost where you garden. At Topeka (Topeka Municipal Airport) that date is April 12, so for spring 2027 onions start indoors Jan 4 to Jan 18, peppers Feb 15 to Mar 1 and tomatoes Feb 22 to Mar 8. Across Kansas's 169 NOAA stations the median last frost runs from Apr 8 to May 2 for the middle 90 percent, so a garden near Brewster 4W starts later than one near Girard.

It depends on the station. The earliest median last spring freeze in Kansas is April 4 at Girard; the latest is May 9 at Brewster 4W. A median is a coin flip: at Topeka the last 32°F freeze comes after April 12 in half of years, and has passed by April 27 in 9 of 10 years (NOAA 1991 to 2020 normals).

UNH Extension sets tomatoes out 1 to 2 weeks after the last frost, which at Topeka is Apr 19 to Apr 26 in 2027. Tomatoes are frost tender, so the date to watch is April 27, when 9 of 10 springs at Topeka have had their last 32°F night. Hardening off starts two weeks before setting out (Apr 5 to Apr 19).

K-State Research and Extension publishes planting months by region (Most of Kansas). For Most of Kansas, tomatoes go in during May. Seeds for transplants go in 4 to 10 weeks ahead of those months, depending on the crop.

K-State Research and Extension's Vegetable Garden Planting Guide puts it this way: "All planting windows are approximate and may need to be adjusted earlier or later depending on the weather each season, varieties chosen, preferred harvest quality, and your location in Kansas." The guide is linked below with the date it was read (September 21, 2026).

UNH Extension gives 8 to 10 weeks from seed to transplant for both, and sets peppers out 2 weeks after the last frost and eggplant 2 to 3 weeks after, so the sowing date is 6 to 8 weeks before the median last frost. At Topeka that is Feb 15 to Mar 1 for peppers.

About two weeks. University of Missouri Extension: "Hardening should be started about two weeks before planting in the garden." University of Minnesota Extension adds that seedlings should go out on a cloudy day or in the late afternoon.

Wichita and Topeka reach a median last frost around Apr 11 to Apr 12, Dodge City around Apr 21, and Goodland on the High Plains near the Colorado line around May 2. Each station carries its own dates: Wichita Apr 11 and Goodland May 2 at the median.