what growing zone is iowa.in
New Plant Hardiness Zone Map Has Iowa in Zone 5. Article | Fri, 01/27/2012 - 09:39 | By Richard Jauron, Jennifer Bousselot, Willy Klein. AMES, Iowa â Gardeners and researchers have a new, updated plant hardiness zone map to consider as they make plant selection decisions this year. The U.S. Department of Agriculture (USDA) released the new version of the map this week â the first update since 1990 â with much of Iowa now considered Zone 5. Plant hardiness zone designations represent the average annual minimum temperatures at a given location.