When to plant cabbage in Montana
Montana’s average last spring frost is May 15, and the first fall frost typically arrives around September 15 — about 123 frost-free days (USDA zones 3a, 3b, 4a, 4b, 5a, 5b, 6a). Cabbage needs 60–100 days to mature, which fits comfortably within Montana's growing season.
Montana covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant cabbage in Montana: the short answer
For a spring planting, plant out Apr 17 – May 4, with seeds started indoors Mar 27 – Apr 10. Seeds germinate in soil from 45 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 cabbage in Montana, step by step
- Start seeds indoors (Mar 27 – Apr 10). Sow seeds ½ inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 75°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs at least six to eight hours of direct sun a day and loose soil at least 18 inches deep, with a pH between 6.0 and 7.5. Dig in compost before planting.
- Plant out (Apr 17 – May 4). Space plants about 15 inches apart in rows 30 inches apart. It handles frost well, so it can go out before the last frost date. As a cool-season crop it does best before summer heat arrives in Montana.
- 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: cabbage worm, cabbage looper, aphids, cabbage root maggot, flea beetle. Diseases and disorders: clubroot, black rot, downy mildew, fusarium yellows.
- Harvest (from about Jun 23 – Aug 2). Cabbage takes 60-100 days to reach harvest. Tighter spacing (12 in) gives smaller heads better for one meal. Split heads mean it is past ready or got a sudden drink after dry weather.
Figures come from our crop data; dates use Montana’s average frost dates. More in the full cabbage growing guide.
Cabbage planting dates by USDA zone in Montana
Montana spans USDA zones 3a, 3b, 4a, 4b, 5a, 5b, 6a. 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 cabbage dates shift with them.
When to plant cabbage in nearby states
Questions gardeners in Montana ask
When is the best time to plant cabbage in Montana?
Plant cabbage transplants outdoors in Montana between April 17 and May 4. That timing is set by Montana's average last spring frost of May 15; Montana spans several climates, so cooler and higher parts of the state run later.
When should I start cabbage seeds indoors in Montana?
Start seeds indoors between March 27 and April 10, about 6 weeks before the last frost, so the seedlings are ready to plant out from April 17.
Can I plant cabbage in the fall in Montana?
Yes. For a fall crop, start transplants between June 6 and June 23, so the crop matures in cool weather before Montana's first frost around September 15.
When will cabbage planted in Montana be ready to harvest?
Planted on time, cabbage is usually ready from about June 23 to August 2, 60-100 days after transplanting.
When is the last frost in Montana?
On average around May 15, with the first fall frost around September 15 - about 123 frost-free days. Your town may differ by two weeks or more.