What plant hardiness zone is Prairie du Rocher

Prairie du Rocher is located at Randolph County, Illinois (IL), USA.

Plant hardiness zone (winter frost zone or gardening zone) for Prairie du Rocher is 6b by the USDA scale.

Coldest zone's winter temperature is −5 … 0 °F.

Plants of 6b USDA hardiness zone suitable for outdoor gardening and growing in this winter frost zone 6b USDA.

Prairie du Rocher, Illinois @ wikipedia.