I probably shouldn’t admit this but one of my all-time favorite movies is Steve Martin’s classic “The Jerk”. Part of the appeal is that I have an affinity for low-brow humor in general but also because the movie contains some great lines; “I was born a poor black child”, and the classic scene when Martin’s character finds his name in the phonebook for the first time and runs around yelling, “The new phonebook’s here! The new phonebook’s here!” http://www.youtube.com/watch?v=kOTDn2A7hcY
I wasn’t quite as excited as Navin R. Johnson today, but pretty darn close. The reason? The USDA (finally) released a new hardiness zone map for the US. http://planthardiness.ars.usda.gov/PHZMWeb/
Why is this exciting news? Well, for several reasons. The earlier version of the USDA map was released 1990. The 22-year-old map had several limitations. First, it was 22 years old. Secondly, the versions of the map that were available electronically did not reproduce well and had poor resolution when you tried to zoom in on a particular area. This sometimes made it difficult to identify the hardiness zone for certain locations and limited the utility of the map for presentations and publications.
There have been persistent rumors for last 6 or 7 years that the USDA would release a better, updated map. In addition to the shortcomings of the old map in terms of resolution, many felt the map didn’t accurately reflect more recent climatic conditions. In 2006 the National Arbor Day Foundation released an updated hardiness map using more current climatic data. This map indicated that many locations were 1 or even 2 hardiness zones warmer than the 1990 USDA map. In addition, the Arbor Day map was available as a hi-res TIF file suitable for PowerPoint presentations and had a ‘zone-finder’ feature based on zip codes.
I haven’t had a lot of time to work with the new USDA map, but my initial reaction is a thumb’s up. Like the Arbor Day map, the new USDA map has a zone finder based on zip code that makes it easy to find the zone in your area. The map is interactive, allowing users to zoom in or out. As with MapQuest and other on-line maps we’ve grown accustomed to, it allows the user to select a roadmap or satellite background and choose different levels of transparency or opacity.
Whenever I discuss hardiness zones, I always include the caveat that these maps are based on average annual minimum temperatures. That is, they are based low temperatures we are likely to see in an average year. Not sure about where you live, but I have yet to see an average year in my adult life. There are many years when we will get below our USDA hardiness zone temperature. Human nature says we want what we can’t have and gardeners love to push the boundaries of their hardiness zone – people in zone 4 love to grow zone 5 plants; people in zone 5 love to grow zone 6 and so on. Just because the new map may say you’re a zone warmer; your climate hasn’t changed, the map is just based on better and more recent data.