What plant hardiness zone is Rocky Boy's Agency

Rocky Boy's Agency is located at Hill County, Montana (MT), USA.

Plant hardiness zone (winter frost zone or gardening zone) for Rocky Boy's Agency is 4a by the USDA scale.

Coldest zone's winter temperature is −30 … -25 °F.

Plants of 4a USDA hardiness zone suitable for outdoor gardening and growing in this winter frost zone 4a USDA.

Rocky Boy's Agency, Montana @ wikipedia.