What plant hardiness zone is Castle Rock

Castle Rock is located at Cowlitz County, Washington (WA), USA.

Plant hardiness zone (winter frost zone or gardening zone) for Castle Rock is 8b by the USDA scale.

Coldest zone's winter temperature is +15 … +20 °F.

Plants of 8b USDA hardiness zone suitable for outdoor gardening and growing in this winter frost zone 8b USDA.

Castle Rock, Washington @ wikipedia.