Tuesday, February 14, 2012

USDA Plant Hardiness Zone Map

Did you know that the USDA Plant Hardiness Zone Map has just been updated? Apparently this is a BIG DEAL. And since this is theoretically a gardening blog, I thought I should bring this to your attention. Last month the USDA released a new map based on the changing climate and over 30 years of data. The previous map was done in 1990 and was based on only 12 years of data, from 1974-1986. The new map also takes into account elevations, winds, proximity to water, all factors that affect plant hardiness.

According to the USDA, "Zones in this edition of the USDA Plant Hardiness Zone Map are based on 1976-2005 weather data. Each zone represents the mean extreme minimum temperature for an area, calculated from the lowest daily minimum temperature recorded for each of the years 1976-2005. This does not represent the coldest it has ever been or ever will be in an area, but it simply is the average of the lowest winter temperatures for a given location for this time period."

I don't pay a lot of attention to the Hardiness Zones, because most of the things I plant are obviously hardy for this area. But the map is important for a new gardener choosing plants for the garden and it might explain why certain annuals and herbs are surviving the winter.  And why I still have allergies in the middle of winter.  Check out this new interactive map and see if your zone may have changed. My zone here in Virginia did change from Zone 6b (average minimum temperature -5 to 0 degrees) to Zone 7a (average minimum temperature 0-5 degrees). Now I am tempted to try a camelia...

And now you know.

1 comment:

  1. I like the zone updates, Ellen, but I was expecting a yummy chocolate cake or some flowers today. Happy Valentines Day.