Iowa Planting Zones

Iowa has an overwhelmingly humid continental climate which limits the number of Iowa planting zones that are found. The entire state experiences extremes on both the cold winter and warm summer fronts with wet springs to round it out. The summers are well known for humidity and heat. Daytime temperatures during the summer months regularly get up to the 90s and have been known to reach triple digits. The average low during winter months will get well into the negatives, often reaching at or below -18 degrees. Annually, Iowa averages about 166 days of sun each year, with close to 200 days of clouds or part clouds. 

Iowa growing zones can range from 4b to 5b, with just the very small southeastern tip of the state getting up to zone 6a. Hardiness, or planting zones, are important to know when planning a garden. Gilmour’s Interactive Planting Zone Map helps gardeners figure out what planting zone they are in as well as determine not only what to grow, but also when to plant it. Iowa planting zones explain which plants will survive and be able to thrive in an area. Zones are determined by first and last frost dates. Frost dates dictate when to plant certain plants to ensure survival. As a general rule of thumb, it is OK to plant anything that grows in your specific zone or lower. This means that if you are in zone 4b, planting anything rated zones 1 to 4 should be fine. Planting plants that are rated for higher zones will increase the likelihood of them not being able to survive harsh winter conditions. 

There are so many plants and flowers to choose from that will do well in Iowa. Daffodils, creeping phlox, peonies, purple coneflowers, daylilies, Virginia bluebells and lily-of-the-valley are all very good options. If looking to plant a vegetable garden, beans and peas, broccoli, cabbage, Brussels sprouts and lettuce all do extremely well in the state.