With winter upon us and how Iowa and the rest of the Midwest has already experienced some extreme temperature and weather fluctuations, we were reminded at Beautiful Land Products of the new plant hardiness maps that were updated in 2012 by the USDA. Since the new 2012 maps have only been out for a few years, one still often sees the older 1990 edition of the USDA plant hardiness zone map which placed large portions of Iowa in a completely different growing zone. The 1990 USDA plant hardiness maps were more general in nature, and for the most part had Iowa split between Zones 4 and 5. The 2012 edition features a greater level of detail and is based on a larger dataset of more recent minimum temperature information from 1976-2005 (as opposed to 1974-1986 for the 1990 maps), which presumably makes the 2012 map more accurate. You can zoom in city by city and see with an intricate level of detail how close you are to the frontier of your growing zone, and plan accordingly.
Portions of Iowa range from Zone 4b to Zone 6a. To put that in perspective, Duluth, Minnesota is in Zone 4b and Santa Fe, New Mexico is just shy of falling within the Zone 6a zone. Just another reminder of the diversity of climate present just in the state of Iowa.
