Sow Asian greens in Kansas twice a year: early March to early April for spring, and the last days of August to about mid-September for fall. Those windows come from counting back from the Wichita reference frost dates. The last spring freeze falls between April 4 and April 18, and the first fall freeze between October 23 and November 2. Fall is the more forgiving season.
The short answer for Kansas
The two windows
Spring sowing starts when the soil can be worked, roughly two to four weeks ahead of the April 4 to April 18 band. That points to early March through early April. Fall sowing runs six to eight weeks ahead of the October 23 to November 2 band, which lands between the end of August and mid-September. Those offsets are my rule of thumb for frost-tolerant greens such as bok choy, tatsoi and mizuna, not figures from NOAA. Calendars for the whole crop are in Growing Asian Greens in Kansas.
| Season | Reference frost band (Wichita) | Sowing window |
|---|---|---|
| Spring | Last freeze, April 4 to April 18 | Early March to early April |
| Fall | First freeze, October 23 to November 2 | Late August to mid-September |
What those frost dates actually measure
They are probabilities, not promises. The figures come from NOAA’s 1991-2020 Climate Normals and describe the 30 to 70 percent band of odds for a 32°F freeze. Inside that band, a freeze after the earlier spring date or before the later fall date is a coin flip, not a surprise.
The numbers also come from one airport weather station in Wichita. Suburban and rural gardens typically see the last spring frost one to two weeks later and the first fall frost one to two weeks earlier, and more than that at elevation. Treat the table as a starting line and shift it for your own ground.
What will not work here
Sowing for a summer harvest
A May or June sowing of bok choy or napa cabbage is the classic Kansas mistake. Long days and rising heat push these plants to bolt, meaning they throw a flower stalk before the head fills out. The roots stay shallow, and a hot, dry, windy stretch dries the top few inches of soil faster than a once-a-week watering can replace it. Kansas has the long season to sow twice, so there is little reason to fight July.
The gap between last and first freeze runs roughly six to seven months. That is generous, and it is also why people assume they can sow whenever they feel like it. Spring crops have to be finished before the heat arrives, and fall crops have to be started while the soil is still warm enough to germinate them.
Sowing too late, or expecting winter survival
October sowings are the opposite problem. Seedlings put in just ahead of a first freeze that could arrive as early as October 23 get days that are shorter and cooler each week. They stall as small rosettes. Baby-leaf mizuna can still work, but a full napa head will not.
Winter is no kinder. The mean daily minimum in the coldest month at the reference station is 22.5°F. That is an average of nights, so some are colder. Tender bok choy will not sit through that unprotected. Hardier greens under row cover or in a cold frame may hold on, but plan them as a bonus, not a crop.
One more trap: assuming the airport date is yours. A rural garden with a late-April frost pocket can lose a March sowing that the Wichita numbers made look safe. Choosing varieties that match these windows helps, and The Best Asian Greens for Kansas covers that side.
What changes across Kansas
Kansas is not one garden. The USDA Plant Hardiness Zone Map (2023, built on 1991-2020 normals) places the state in zones 5b to 7a. Hardiness zones rest on one variable, the average annual extreme minimum temperature. From 5b to 7a is a spread of about 15°F in that measure, so there is no single answer for the whole state.
Readers in the cooler north and at higher elevation in the west should lean later in spring and earlier in fall. Shift the spring window back a week or two, and pull the fall sowing forward by the same margin. Readers in the warmer south have more room on both ends, though they also meet heat sooner. The reference-city frost dates sit between those extremes, and that is why they are a starting point rather than a rule.
Which zone applies to you is not something this page can say. Look up your own location on the USDA Plant Hardiness Zone Map and read the result for your ZIP code. Keep in mind that the zone is a winter-cold number. It tells you little about how fast the soil warms in March or how hot your August runs, which matter more for sowing dates.
Where to check this for your own county
Your county office of K-State Research and Extension is the best next stop. Look for two things: the local planting calendar, and any vegetable varieties that have been trialled in your county. Trial results tell you which cultivars bolted, which held through the first hard freeze, and which sowing dates worked on soil like yours.
The county agent can also tell you how far your local frost dates run from the Wichita figures. A recommendation built on years of local records beats a state-level one. This page is the state-level one. It gives you a defensible frame and the reasoning behind it, but it cannot see your valley, your windbreak or your clay.
This page does not have a Kansas county-by-county table of frost dates, and it will not make one up. When the extension calendar and this page disagree, trust the extension calendar.
Checking this against your own garden
Your garden outranks every date above. Three things are worth watching, and none needs more than your hands and eyes.
- Soil warmth by feel. In spring, push a hand into the bed. If it is cold and clumps in a wet ball, seeds will sit and rot. A bed that crumbles and feels merely cool is ready. Beds that warm first show you where your early sowings belong.
- First true leaves. The first pair of leaves are the seed leaves. The next, with the plant’s real shape, are the true leaves. If seedlings take weeks to reach them, your soil is running colder than the calendar assumes.
- Where frost lingers. Walk out at dawn after a cold night. Frost that stays on grass in one corner and not another marks a frost pocket, and that corner should get your late fall sowing last and your spring sowing later.
Write down what you see for one year and your own calendar will tighten around these dates.
Common questions
Is spring or fall better for Asian greens in Kansas?
Fall tends to be easier. Seedlings start in warm soil, mature in cooling weather, and bolting pressure is lower. Spring works, but the window closes as heat arrives.
Can a late freeze after sowing ruin the crop?
Hardy seedlings can handle a light frost, but a hard freeze can set them back. Since a freeze after April 4 to April 18 is a coin flip, keep row cover on hand for spring sowings.
Can I sow in winter under cover?
You can try. The coldest-month mean minimum at the reference station is 22.5°F, so a cold frame or row cover is mandatory, and results will vary by variety. Treat it as an experiment.
Are the Wichita frost dates mine?
Probably not exactly. They describe an airport station. Suburban and rural gardens often see later spring frosts and earlier fall frosts, and more so at elevation, so check your county before committing.