When to plant lettuce 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). Lettuce needs 30–60 days to mature, which fits comfortably within Illinois's growing season.
When to plant lettuce in Illinois: the short answer
For a spring planting, plant out Mar 30 – Apr 16, with seeds started indoors Mar 16 – Mar 30. Seeds germinate in soil from 35 to 80°F.
Succession sow again in Illinois: Apr 18 · Apr 30 · May 12 · May 24
Spring succession stops before summer heat makes it bolt. Start sowing again in late summer for a fall crop (see the fall window above).
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 lettuce in Illinois, step by step
- Start seeds indoors (Mar 16 – Mar 30). Sow seeds ⅛ inch deep in seed-starting mix under bright light. They take 2-10 days to sprout, fastest in soil around 65°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 8 inches deep, with a pH between 6.0 and 7.0. Dig in compost before planting.
- Plant out (Mar 30 – Apr 16). Space plants about 10 inches apart in rows 14 inches apart. It tolerates a light frost but not a hard freeze. 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: aphids, slugs, snails, cutworm. Diseases and disorders: downy mildew, bottom rot, tipburn (calcium disorder).
- Harvest (from about May 6 – Jun 5). Lettuce takes 30-60 days to reach harvest. Seed needs light - barely cover it. Will not germinate above ~80 F soil. Loose-leaf types give the fastest, most forgiving cut-and-come-again harvest.
Figures come from our crop data; dates use Illinois’s average frost dates. More in the full lettuce growing guide.
Lettuce 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 lettuce dates shift with them.
When to plant lettuce in nearby states
Questions gardeners in Illinois ask
When is the best time to plant lettuce in Illinois?
Plant lettuce transplants outdoors in Illinois between March 30 and April 16. That timing is set by Illinois's average last spring frost of April 20.
When should I start lettuce seeds indoors in Illinois?
Start seeds indoors between March 16 and March 30, about 4 weeks before the last frost, so the seedlings are ready to plant out from March 30.
Can I plant lettuce in the fall in Illinois?
Yes. For a fall crop, sow between August 9 and August 26, so the crop matures in cool weather before Illinois's first frost around October 14.
When will lettuce planted in Illinois be ready to harvest?
Planted on time, lettuce is usually ready from about May 6 to June 5, 30-60 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.