When to plant spinach 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). Spinach needs 37–45 days to mature, which fits comfortably within Iowa's growing season.
When to plant spinach in Iowa: the short answer
For a spring planting, sow Mar 16 – Apr 4. Seeds germinate in soil from 35 to 75°F.
Succession sow again in Iowa: Apr 2 · Apr 14 · Apr 26 · May 8 · May 20
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 spinach in Iowa, step by step
- 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 12 inches deep, with a pH between 6.0 and 7.5. Dig in compost before planting.
- Sow outdoors (Mar 16 – Apr 4). Space plants about 4 inches apart in rows 12 inches apart, sowing seed ½ inch deep. 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 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: leaf miner, aphids, flea beetle. Diseases and disorders: downy mildew, white rust, damping off.
- Harvest (from about Apr 27 – May 5). Spinach takes 37-45 days to reach harvest. Bolts fast in heat and long days - it is really a spring and fall crop. A late-fall sowing under row cover often overwinters for an early-spring cut.
Figures come from our crop data; dates use Iowa’s average frost dates. More in the full spinach growing guide.
Spinach 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 spinach dates shift with them.
When to plant spinach in nearby states
Questions gardeners in Iowa ask
When is the best time to plant spinach in Iowa?
Sow spinach in Iowa between March 16 and April 4. That timing is set by Iowa's average last spring frost of April 25.
Can I plant spinach in the fall in Iowa?
Yes. For a fall crop, sow between August 10 and August 27, so the crop matures in cool weather before Iowa's first frost around October 8.
When will spinach planted in Iowa be ready to harvest?
Planted on time, spinach is usually ready from about April 27 to May 5, 37-45 days after sowing.
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.