September 14, 2012

Keeping up with the heat

Filed under: Uncategorized — jchatoff @ 12:07 am
Tags: , , , ,

In about three months and change, sometime after the first of the year when the winter already seems too long and there’s no end in sight, gardeners will began to plan. First, they will send away for seed catalogues and when those arrive, evenings will be spent turning page after page of bright glossy photos of everything from acacia to zinnias, amaranthus to zucchini.

But before they can put a check mark next to the new hybrid double lantana, most gardeners will look on the map in the middle of the catalogue, just to be sure they remember their hardiness zone.

For years, the hardiness zone map produced by the US Department of Agriculture has been the go-to indicator of plant survival for every gardener in every corner of the country.  If you live in Zone 5, pass on the boxwood and think Amur River privet instead.  The USDA knows what will survive your tough winters and what won’t.

At least they have until recently.  The first USDA map came out in 1960, was revised in 1965, and that was pretty much it until 1990, when a new map was issued, based on double the number of observation stations.  That was good until this past January, when a new map was issued.

 But that one is already out of date, according to Dr.Nir Krakauer, a civil engineering professor at City College in New York.

“Over one-third of the country has already shifted half-zones compared to the current release, and over one-fifth has shifted full zones,” Professor Krakauer has written. (Read the full article  here.)

The changes are thick and fast because, Krakauer points out, winter temperatures are rising faster than summer temperatures.  And if you live in the eastern half of the country, it’s happening faster than in the southwest and of course, it’s faster for the interior than coastal areas.

At first, I imagine Northerners will enjoy growing camellias and Southerners will be happy to plant tropical stuff, but eventually we’ll have to depend on the farmers of Manitoba and Siberia to feed us.


  1. The Arborday Foundation has always had better hardiness information than the USDA. They say the 2012 USDA map is similar to their 2006 map. See:
    Presumably the trends have continued for the last 6 years, too.


    Comment by Jane — September 14, 2012 @ 6:17 am | Reply

  2. Weather and Time are relentless… they keep pushing forward! We all must to our part to make life livable.


    Comment by GALYA TARMU — September 15, 2012 @ 1:00 pm | Reply

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