When to plant tomatoes 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). Tomato needs 60–85 days to mature, which fits comfortably within Iowa's growing season.
When to plant tomatoes in Iowa: the short answer
For a spring planting, plant out Apr 25 – May 12, with seeds started indoors Feb 28 – Mar 14. Wait until the soil is at least 50°F and frost is over.
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 tomatoes in Iowa, step by step
- Start seeds indoors (Feb 28 – Mar 14). Sow seeds ¼ inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 80°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. They need at least six to eight hours of direct sun a day and loose soil at least 18 inches deep, with a pH between 5.5 and 7.5. Dig in compost before planting.
- Plant out (Apr 25 – May 12). Space plants about 24 inches apart in rows 36 inches apart. It is killed by frost, so nothing goes outside until the danger has passed.
- 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: tomato hornworm, aphids, whitefly, flea beetle. Diseases and disorders: early blight, late blight, septoria leaf spot, fusarium wilt, blossom-end rot (calcium disorder).
- Harvest (from about Jul 1 – Jul 26). Tomato takes 60-85 days to reach harvest. Days to maturity counted from transplant. Bury 2/3 of the stem at transplanting for extra roots. Determinate types suit containers and one big harvest; indeterminate types need staking and produce until frost.
Figures come from our crop data; dates use Iowa’s average frost dates. More in the full tomato growing guide.
Tomato 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 tomato dates shift with them.
When to plant tomatoes in nearby states
Questions gardeners in Iowa ask
When is the best time to plant tomatoes in Iowa?
Plant tomato transplants outdoors in Iowa between April 25 and May 12. That timing is set by Iowa's average last spring frost of April 25.
When should I start tomato seeds indoors in Iowa?
Start seeds indoors between February 28 and March 14, about 7 weeks before the last frost, so the seedlings are ready to plant out from April 25.
What is the latest I can plant tomatoes in Iowa?
About August 9. Tomatoes need at least 60 days to mature after transplanting, and frost around October 8 ends the season, so later plantings risk being cut short.
When will tomatoes planted in Iowa be ready to harvest?
Planted on time, tomatoes are usually ready from about July 1 to July 26, 60-85 days after transplanting.
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.