What plant hardiness zone is Pompeys Pillar

Pompeys Pillar is located at Yellowstone County, Montana (MT), USA.

Plant hardiness zone (winter frost zone or gardening zone) for Pompeys Pillar 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.

Pompeys Pillar, Montana @ wikipedia.