When to plant kale 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). Kale needs 50–65 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 kale 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 kale 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 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 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 16 inches apart in rows 20 inches apart. 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 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, cabbage aphid, flea beetle, harlequin bug. Diseases and disorders: black rot, clubroot, downy mildew.
- Harvest (from about Jun 13 – Jun 28). Kale takes 50-65 days to reach harvest. Flavour turns sweet after a hard frost, so the fall crop is the good one. Pick lower leaves and let the plant keep growing upward.
Figures come from our crop data; dates use Montana’s average frost dates. More in the full kale growing guide.
Kale 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 kale dates shift with them.
When to plant kale in nearby states
Questions gardeners in Montana ask
When is the best time to plant kale in Montana?
Plant kale 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 kale 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 kale in the fall in Montana?
Yes. For a fall crop, sow between June 20 and July 7, so the crop matures in cool weather before Montana's first frost around September 15.
When will kale planted in Montana be ready to harvest?
Planted on time, kale is usually ready from about June 13 to June 28, 50-65 days after planting.
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.