When to plant swiss chard in Wisconsin
Wisconsin’s average last spring frost is May 10, and the first fall frost typically arrives around September 30 — about 143 frost-free days (USDA zones 3b, 4a, 4b, 5a, 5b). Swiss Chard needs 50–60 days to mature, which fits comfortably within Wisconsin's growing season.
When to plant swiss chard in Wisconsin: the short answer
For a spring planting, plant out Apr 19 – May 6, with seeds started indoors Apr 5 – Apr 19. 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 Wisconsin, step by step
- Start seeds indoors (Apr 5 – Apr 19). 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 (Apr 19 – May 6). 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 Wisconsin.
- 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 Jun 15 – Jun 25). 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 Wisconsin’s average frost dates. More in the full swiss chard growing guide.
Swiss Chard planting dates by USDA zone in Wisconsin
Wisconsin spans USDA zones 3b, 4a, 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 swiss chard dates shift with them.
When to plant swiss chard in nearby states
Questions gardeners in Wisconsin ask
When is the best time to plant swiss chard in Wisconsin?
Plant swiss chard transplants outdoors in Wisconsin between April 19 and May 6. That timing is set by Wisconsin's average last spring frost of May 10.
When should I start swiss chard seeds indoors in Wisconsin?
Start seeds indoors between April 5 and April 19, about 4 weeks before the last frost, so the seedlings are ready to plant out from April 19.
Can I plant swiss chard in the fall in Wisconsin?
Yes. For a fall crop, sow between July 12 and July 29, so the crop matures in cool weather before Wisconsin's first frost around September 30.
When will swiss chard planted in Wisconsin be ready to harvest?
Planted on time, swiss chard is usually ready from about June 15 to June 25, 50-60 days after planting.
When is the last frost in Wisconsin?
On average around May 10, with the first fall frost around September 30 - about 143 frost-free days. Your town may differ by two weeks or more.