Understanding USDA Updates To Plant Hardiness Zone Map

    Published: 06-16-2009
    Views: 16,601
    Master gardener William Moss discusses the recent updates the USDA made to their Plant Hardiness Zone Map due to warmer temperatures.

    William Moss: Yes to robins are returning sooner if they leave at all, and yes to irises that are blooming earlier. Gardeners have sense to shifting the climate for a quite a while and now science backs it up. Today, we are talking about the new USDA horizon map. This map basically tells the minimum temperatures in your zone. It's really good for gardeners because they will know what plants can handle the temperatures. Some plants can take going to -25, while others can only takes may be going to 32 degrees. So the horizon map is a good tool for gardeners to have so they can know what plants will succeed in their area. On the old map, Chicago was a Zone 5 and New York was a Zone 6. But on the new map you will see Chicago is up to Zone 6 and New York is Zone 7. Basically the zones have shifted up and this is just reflective of the warmer climate in these areas. This is both good news and bad news. The good news is that most gardeners will enjoy a longer growing season and also they may be able to grow plants they couldn't before. For instance, northerners may be able to grow crape myrtles which have long been a southern favorite. The bad news is the warming temperatures would allow invasive pest to spread so look for fire ants, kudzu and others to advance further. Regardless of the reason, our climate is changing and gardeners can prepare for a little longer season. Get out and grow.