When to plant swiss chard 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). Swiss Chard needs 50–60 days to mature, which fits comfortably within Illinois's growing season.
When to plant swiss chard 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 40 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 swiss chard in Illinois, step by step
- Start seeds indoors (Mar 16 – Mar 30). Sow seeds 0.75 inch deep in seed-starting mix under bright light. They take 5-14 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 12 inches deep, with a pH between 6.0 and 7.5. Dig in compost before planting.
- Plant out (Mar 30 – Apr 16). Space plants about 9 inches apart in rows 18 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: leaf miner, aphids, flea beetle. Diseases and disorders: cercospora leaf spot, downy mildew.
- Harvest (from about May 26 – Jun 5). Swiss Chard takes 50-60 days to reach harvest. One of the most heat-tolerant leafy greens - a single spring sowing usually carries through summer into fall if kept picked.
Figures come from our crop data; dates use Illinois’s average frost dates. More in the full swiss chard growing guide.
Swiss Chard 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 swiss chard dates shift with them.
When to plant swiss chard in nearby states
Questions gardeners in Illinois ask
When is the best time to plant swiss chard in Illinois?
Plant swiss chard 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 swiss chard 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 swiss chard in the fall in Illinois?
Yes. For a fall crop, sow between July 26 and August 12, so the crop matures in cool weather before Illinois's first frost around October 14.
When will swiss chard planted in Illinois be ready to harvest?
Planted on time, swiss chard is usually ready from about May 26 to June 5, 50-60 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.