Winter can be tough on Iowa's trees and shrubs.
Low temperatures, rapid temperature changes, winter desiccation, and the weight of ice and snow can damage vulnerable trees and shrubs. Iowa is located in USDA Hardiness Zones 4 and 5. The dividing line between Zones 4 and 5 lies roughly from Shenandoah to Ames to Dubuque. Woody plants gradually acclimate to cold temperatures. Cold hardiness is initiated by decreasing daylength and temperature.