When to plant Chinese cabbage in Montana

In spring, from Apr 1 – May 15 in Great Falls to May 20 – June 1 in Butte-Silver Bow (balance).

In fall, from May 15 – June 15 in Butte-Silver Bow (balance) to June 15 – Aug 1 in Billings.

USDA's earliest safe spring and latest safe fall planting dates, matched to each place's average frost dates.

Chinese cabbage planting dates by place in Montana
PlaceSpringFall
BelgradeMay 10 – June 15June 1 – July 1
BillingsFall-plantedJune 15 – Aug 1
BozemanMay 10 – June 15June 1 – July 1
Butte-Silver Bow (balance)May 20 – June 1May 15 – June 15
Great FallsApr 1 – May 15June 1 – July 15
HelenaApr 1 – May 15June 1 – July 15
KalispellMay 10 – June 15May 15 – June 15
MissoulaApr 1 – May 15June 1 – July 15

Planting dates: USDA Home and Garden Bulletin No. 9 (1967), tables 4 and 5. Frost dates: NOAA U.S. Climate Normals 1991–2020. “—” means the place's frost date is outside the table. The full USDA table for chinese cabbage.