When to plant basil in Montana

Plant out in Billings

May 11–May 25

Across Montana the window opens between May 11 and June 20. Find your city below; the dates follow each town's own average last frost.

Start indoors, Billings: Mar 23–Apr 6
Plant out, Billings: May 11–May 25
Sow outdoors, Billings: May 11–May 25
Last sowing for a harvest: Jul 10
Last frost, Billings: May 4

Start seeds indoors 4–6 weeks before the last frost; plant out 1–3 weeks after the last frost; sow outdoors 1–3 weeks after the last frost. Basil blackens below 50°F. Wait a week or two after the last frost.

Basil planting dates by city

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost

JanFebMarAprMayJunJulAugSepOctNovDec

BillingsMay 11–May 25

MissoulaMay 17–May 31

Great FallsMay 13–May 27

BozemanJun 2–Jun 16

Butte-Silver BowJun 20–Jul 4

HelenaMay 16–May 30

KalispellJun 7–Jun 21

In Butte-Silver Bow the frost-free season is shorter than basil need. Start plants indoors and pick early varieties.

Questions

When should I plant basil in Montana?

In Billings, plant out from May 11 to May 25. Across Montana the window opens between May 11 and June 20, depending on the local last frost.

How is this date worked out?

Start seeds indoors 4–6 weeks before the last frost; plant out 1–3 weeks after the last frost; sow outdoors 1–3 weeks after the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.

Is the season long enough for basil everywhere in Montana?

Not quite. In Butte-Silver Bow the frost-free season is shorter than the time basil need to ripen. Start plants indoors and pick an early variety.