When to plant chinese cabbage (napa) in Chicago, Illinois
March 20 – March 27
Transplant outdoors · typical Chicago yearClimate basis: NOAA station Chicago Northerly Is, IL (USC00111550), 2 mi (3 km) from downtown Chicago (ZCTA 60602 centroid), elevation 583 ft, on the 1991–2020 climate normals. Transplant chinese cabbage (napa) outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 10). One year in ten still freezes after April 25.
The Chicago year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Apr 25
Every method, with its sources
Start seeds indoors
Feb 13 – Feb 27Arkansas Extension requires transplants no older than "four to five weeks" at setting out, so indoor sowing is counted back 28–35 days from the cited transplant window, giving last spring frost minus 56 to minus 42 days. Anchored to the median last spring freeze (Apr 10). University of Arkansas System Division of Agriculture, Cooperative Extension Service · Clemson Cooperative Extension, Home & Garden Information Center · Clemson Cooperative Extension, Home & Garden Information Center
Transplant outdoors
Mar 20 – Mar 27Arkansas Extension states "Transplant two to three weeks before the last frost-free date", giving last spring frost minus 21 to minus 14 days; Clemson's warning that spring-frosted seedlings bolt is a caution on the same window, not a competing interval. Anchored to the median last spring freeze (Apr 10). Clemson Cooperative Extension, Home & Garden Information Center · Clemson Cooperative Extension, Home & Garden Information Center
Variety assumption: Offsets assume spring-set transplants of the 45–72 day Napa and Michihili types tabulated by Arkansas Extension; no fall window is encoded because every fall rule found for napa is fixed-calendar ("early to midsummer", "July") rather than frost-anchored.
These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.
Crop rule sources (3)
- University of Arkansas System Division of Agriculture, Cooperative Extension Service: Chinese Cabbage (Home Gardening Series, FSA6066) (accessed 2026-07-25)"Transplant two to three weeks before the last frost-free date and before the plants are too old (four to five weeks)."
- Clemson Cooperative Extension, Home & Garden Information Center: Chinese Vegetables (accessed 2026-07-25)"Chinese cabbage is best sown in late summer and autumn rather than spring. If seed is sown in spring, young plants may bolt if they are frosted or exposed to long, cold nights."
- Clemson Cooperative Extension, Home & Garden Information Center: Cabbage & Chinese Cabbage (accessed 2026-07-25)