new plant hardiness zones ?

I wonder if this will include Canada ? I can’t find a new map for my country, but I have heard about it on several local news stations.

For the first time since 1990 the U.S. Department of Agriculture has revised the official guide and it seems like almost everything has changed. Ohio, Nebraska and Texas are in warmer zones.
“The Zone Map is a mainstay of 80 million home gardeners, showing the average annual extreme minimum temperatures at a given location during a particular time period. Gardeners use the maps to determine whether seed and plant varieties are likely to survive in their areas.”

I know this can be bad news for crops and for much of the agricultural world. But, I can’t help but feel a smidgen of joy that the climate around us is getting warmer. I know I know, shame on me for saying it. Global warming is bad.
Many plants and shrubs I’d love to grow but can’t because of my cold zone just may come true someday. I mean, so far this winter with the temperatures we’ve been having puts my area at like a zone 7a. Although, last year at this very same time we were experiencing -30C for a few days straight. Hello zone 4. Brrr.

It also looks as though new zones were added in for Hawaii and Puerto Rico – 12 and 13, meaning that their winters are warmer than ever. Not like they get cold winters anyway, but still, that’s a major change. Also, for the first time, calculations include more detailed factors such as prevailing winds, the presence of nearby bodies of water, the slope of the land, and the way cities are hotter than suburbs and rural areas.

Gardeners have known for a while that the climate is changing, it’s not really big news to us. We know what works for our area – what will grow and thrive, what won’t.  Though it’s great that the federal government is keeping us gardeners informed with what the plants have always known… where they can survive.


9 thoughts on “new plant hardiness zones ?

  1. Strange that they did not include a revised Canadian map. There is quite a discussion going on about this new hardiness zone map over on Margaret Roach’s blog,

    The makers of the map claim it is not a climate change study, but rather a re-zoning based on several new factors they’ve taken into account. Still, everywhere you look it’s getting gradually warmer, so it’s hard not to attribute it to global warming.

    We moved up a half-zone, but it won’t make much of a difference here – especially when things can be so different from year to year, this winter and last winter being a perfect example, as you point out.

    I guess you’re always safe sticking with native plants who, as you say, know where they can survive. Of course I’m also drawn to those that are not native and are sometimes borderline for our zone!

  2. Yes, I live in Delaware, USA, and they are “contemplating” changing the southern part of the state. We’re Zone 7, and we’ve had a rather warm season. Daffodil shoots are suspended in flight about three inches, and at least eight more weeks of winter. But those of us (as you point out) that are seasoned gardeners are aware from season to season of the unpredictability of Mother Nature. Thanks, Sally

  3. Here in Wyoming it seems like we are having a warm winter, but as I did a quick check against the 100 year averages it is quite normal (actually Nov and Dec were a little colder than the 100 year avg), and the overall trend is cooling temps.

    I give more details in my latest post

    So it’s a little puzzling to me why the area around Casper, Wyoming has been changed to a warmer hardiness zone. Guess I have more digging to do.

  4. What I’m seeing in practice is not so much straight-up unidirectional weather change (though I have clearly watched the patterns or cycles alter over the last 30-40 years or so) as it is a move toward the extremes: the hot is hotter, the cold colder, and the periods of each longer, at least in most places I’ve spent serious amounts of time. I’ve yet to ‘get the hang of’ Texas gardening–only been here a couple of years so far!

  5. @kathriningrid, yes I wondered about that very thing. I hope to get the time to look a little closer at the data- especially the maximum and minimum temps over time. Wyoming is known for extremes and deep fluctuations within 24 hour time frames, so seeing anything obvious might take more expertise than I have.

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