When to plant lettuce in Iowa
Iowa’s average last spring frost is April 25, and the first fall frost typically arrives around October 8 — about 166 frost-free days (USDA zones 4b, 5a, 5b). Lettuce needs 30–60 days to mature, which fits comfortably within Iowa's growing season.
When to plant lettuce in Iowa: the short answer
For a spring planting, plant out Apr 4 – Apr 21, with seeds started indoors Mar 21 – Apr 4. Seeds germinate in soil from 35 to 80°F.
Succession sow again in Iowa: Apr 23 · May 5 · May 17 · May 29
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 Iowa, step by step
- Start seeds indoors (Mar 21 – Apr 4). 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 (Apr 4 – Apr 21). 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 Iowa.
- 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 11 – Jun 10). 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 Iowa’s average frost dates. More in the full lettuce growing guide.
Lettuce planting dates by USDA zone in Iowa
Iowa spans USDA zones 4b, 5a, 5b. 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 Iowa ask
When is the best time to plant lettuce in Iowa?
Plant lettuce transplants outdoors in Iowa between April 4 and April 21. That timing is set by Iowa's average last spring frost of April 25.
When should I start lettuce seeds indoors in Iowa?
Start seeds indoors between March 21 and April 4, about 4 weeks before the last frost, so the seedlings are ready to plant out from April 4.
Can I plant lettuce in the fall in Iowa?
Yes. For a fall crop, sow between August 3 and August 20, so the crop matures in cool weather before Iowa's first frost around October 8.
When will lettuce planted in Iowa be ready to harvest?
Planted on time, lettuce is usually ready from about May 11 to June 10, 30-60 days after planting.
When is the last frost in Iowa?
On average around April 25, with the first fall frost around October 8 - about 166 frost-free days. Your town may differ by two weeks or more.