What plant hardiness zone is Saint Olaf

Saint Olaf is located at Clayton County, Iowa (IA), USA.

Plant hardiness zone (winter frost zone or gardening zone) for Saint Olaf is 4b by the USDA scale.

Coldest zone's winter temperature is −25 … -20 °F.

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

Saint Olaf, Iowa @ wikipedia.