When to plant swiss chard in Oklahoma
Oklahoma’s average last spring frost is April 1, and the first fall frost typically arrives around November 1 — about 214 frost-free days (USDA zones 6b, 7a, 7b, 8a). Swiss Chard needs 50–60 days to mature, which fits comfortably within Oklahoma's growing season.
When to plant swiss chard in Oklahoma: the short answer
For a spring planting, plant out Mar 11 – Mar 28, with seeds started indoors Feb 25 – Mar 11. 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 Oklahoma, step by step
- Start seeds indoors (Feb 25 – Mar 11). 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 11 – Mar 28). 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 Oklahoma.
- 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 7 – May 17). 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 Oklahoma’s average frost dates. More in the full swiss chard growing guide.
Swiss Chard planting dates by USDA zone in Oklahoma
Oklahoma spans USDA zones 6b, 7a, 7b, 8a. 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
| State | Last frost | Plant out |
|---|---|---|
| Oklahoma (this page) | April 1 | Mar 11 – Mar 28 |
| North Dakota | May 15 | Apr 24 – May 11 |
| South Dakota | May 10 | Apr 19 – May 6 |
| Nebraska | April 30 | Apr 9 – Apr 26 |
| Kansas | April 15 | Mar 25 – Apr 11 |
Questions gardeners in Oklahoma ask
When is the best time to plant swiss chard in Oklahoma?
Plant swiss chard transplants outdoors in Oklahoma between March 11 and March 28. That timing is set by Oklahoma's average last spring frost of April 1.
When should I start swiss chard seeds indoors in Oklahoma?
Start seeds indoors between February 25 and March 11, about 4 weeks before the last frost, so the seedlings are ready to plant out from March 11.
Can I plant swiss chard in the fall in Oklahoma?
Yes. For a fall crop, sow between August 13 and August 30, so the crop matures in cool weather before Oklahoma's first frost around November 1.
When will swiss chard planted in Oklahoma be ready to harvest?
Planted on time, swiss chard is usually ready from about May 7 to May 17, 50-60 days after planting.
When is the last frost in Oklahoma?
On average around April 1, with the first fall frost around November 1 - about 214 frost-free days. Your town may differ by two weeks or more.