When to plant kale in Illinois
Illinois’s average last spring frost is April 20, and the first fall frost typically arrives around October 14 — about 177 frost-free days (USDA zones 5a, 5b, 6a, 6b, 7a). Kale needs 50–65 days to mature, which fits comfortably within Illinois's growing season.
When to plant kale in Illinois: the short answer
For a spring planting, plant out Mar 23 – Apr 9, with seeds started indoors Mar 2 – Mar 16. Seeds germinate in soil from 45 to 85°F.
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow kale in Illinois, step by step
- Start seeds indoors (Mar 2 – Mar 16). Sow seeds ½ inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 70°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs six or more hours of sun for the best growth, though four to six hours in partial shade is enough and loose soil at least 18 inches deep, with a pH between 6.0 and 7.5. Dig in compost before planting.
- Plant out (Mar 23 – Apr 9). Space plants about 16 inches apart in rows 20 inches apart. It tolerates hard frost, so it is one of the first crops to plant. As a cool-season crop it does best before summer heat arrives in Illinois.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: cabbage worm, cabbage looper, cabbage aphid, flea beetle, harlequin bug. Diseases and disorders: black rot, clubroot, downy mildew.
- Harvest (from about May 19 – Jun 3). Kale takes 50-65 days to reach harvest. Flavour turns sweet after a hard frost, so the fall crop is the good one. Pick lower leaves and let the plant keep growing upward.
Figures come from our crop data; dates use Illinois’s average frost dates. More in the full kale growing guide.
Kale planting dates by USDA zone in Illinois
Illinois spans USDA zones 5a, 5b, 6a, 6b, 7a. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the kale dates shift with them.
When to plant kale in nearby states
Questions gardeners in Illinois ask
When is the best time to plant kale in Illinois?
Plant kale transplants outdoors in Illinois between March 23 and April 9. That timing is set by Illinois's average last spring frost of April 20.
When should I start kale seeds indoors in Illinois?
Start seeds indoors between March 2 and March 16, about 6 weeks before the last frost, so the seedlings are ready to plant out from March 23.
Can I plant kale in the fall in Illinois?
Yes. For a fall crop, sow between July 19 and August 5, so the crop matures in cool weather before Illinois's first frost around October 14.
When will kale planted in Illinois be ready to harvest?
Planted on time, kale is usually ready from about May 19 to June 3, 50-65 days after planting.
When is the last frost in Illinois?
On average around April 20, with the first fall frost around October 14 - about 177 frost-free days. Your town may differ by two weeks or more.