What plant hardiness zone is Irwin
Irwin is located at Bonneville County, Idaho (ID), USA.
Plant hardiness zone (winter frost zone or gardening zone) for Irwin is 5a by the USDA scale.
Coldest zone's winter temperature is −20 … -15 °F.
Plants of 5a USDA hardiness zone suitable for outdoor gardening and growing in this winter frost zone 5a USDA.