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This map lists all of Iowa asThis map lists all of Iowa as Zone 2, but living in northern Iowa all of my life I know that planting dates and last frost predictions etc. fall more accurately into Zone 3, i.e. May 15th has always been the earliest planting date based on local wisdom. If you look at the map visually you can see where northern Iowa should really be considered Zone 3 based on the demarcation line for neighboring states/regions.

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