New Plant Zone Hardiness map released. (grow, tree, solar, violet)

[wit-nit]

USDA relaeases new updated plant zone hardiness map Jan 25, 2012 to reflect changes in Global warming etal.

USDA Plant Hardiness Zone Map

[Ohiogirl81]

We're movin' on up.

Guess those perennials I planted 3 years ago for Zone 7a, when my house was still in Zone 6b, won't die now!

[motordavid]

Still "6a", at our Mtn Joint, at 5,000 ft...
The old Zone map didn't give our area full consideration of the winter/late spring at that altitude, and the new one does not either, imo.
And, I understand micro climes and how some 'stuff' works in Zone, and some 'stuff' does not...

Add in the annual late hard freezes, over the past decade, the tree buds finally turning to leaves in mid-May earliest, the annual snow in October,
and it's still Zone 5b/barely 6a to me.

But, thanks for the link... Interesting.
BR, mD

[J&Em]

It is about time. Thanks for posting it.

Use this combination map The Arbor Day Foundation to see the changes just from 1990-2006 to see why they have had to make the change. It can give you an idea why some areas have not changed or changed very little while others have changed whole zones.

Just be aware that a lot of publications and catalogs have not updated their maps from the 1990's when making up your mind to order a borderline plant.

[Bulldogdad]

Careful people. We are in a La Nina weather pattern which is drier and colder that the El Nino's that dominated that period. Plus we are near or at the end of the Solar maximum.

Like J&Em stated becareful if you are in a border area.

[goldengrain]

From the Washington Post:

New USDA plant zones clearly show climate change


New USDA plant zones clearly show climate change - Capital Weather Gang - The Washington Post


Reporting for the Associated Press (http://www.washingtonpost.com/lifestyle/home-garden/figs-in-boston-area-now-you-can-grow-them-new-federal-planting-map-adjusts-to-warmer-winters/2012/01/25/gIQAGZaeQQ_story.html - broken link), Seth Borenstein spoke with David Wolfe, a professor of plant and soil ecology at Cornell, who agreed USDA is being “too cautious” in laying off the climate change connection

[GraniteStater]

While it is definitely true that temperatures are rapidly warming in most areas, the USDA plant hardiness zones don't accurately depict microclimates, account for heat islands, and other factors. What about an extreme cold snap with temperatures 10-15F lower than the coldest hardiness zone range a location supposedly belongs in, even with the warming? It seems to me that extremes of all types will become more common. Some locations have low temperatures that are highly variable depending on the winter. In NH, the coldest it has been this winter has been -7F while a few years ago it was -24F. I don't know how an accurate zone can be determined when the coldest temperature each winter can vary by 15-20F in some locations?

[Bulldogdad]

The reason the USDA steered clear of the obvious political debate is because the data for the new map only encompasses a brief time span. And dosen't take into account any factors other than recorded temperatures.

[SCGranny]

WTH???

I went from a 5b to a 4b!

Guess global warming doesn't exist here.

[J&Em]

Originally Posted by goldengrain

From the Washington Post:

New USDA plant zones clearly show climate change


New USDA plant zones clearly show climate change - Capital Weather Gang - The Washington Post


Reporting for the Associated Press (http://www.washingtonpost.com/lifestyle/home-garden/figs-in-boston-area-now-you-can-grow-them-new-federal-planting-map-adjusts-to-warmer-winters/2012/01/25/gIQAGZaeQQ_story.html - broken link), Seth Borenstein spoke with David Wolfe, a professor of plant and soil ecology at Cornell, who agreed USDA is being “too cautious” in laying off the climate change connection

The same articles quote the meteorologist who helped create the map that there isn't enough data to make any such claim. The map was intended to reflect coldest averages not trends and not the most extreme temperatures ever recorded. Much as a lot of people want to believe every warm day, season, year or even decade is an indication of a long term trend, we have had so many warm and cold cycles come and go just in the period of written history that a 13 year or even a 30 year period is a comparative sneeze. As Bulldogdad mentions La Nina and El Nino cycles have made differences, as have sun cycles. The media makes it sound so simple but there is much, much more to it.

The map makers attributed much more of the changes in zone to better data than any real big weather changes. The two maps begin nearly at the same time (1974 and 1976) but one stopped after 13 years the next covered about 30 years. The difference is a mere decade and a half. The second was more the one that was based on more precise data as well as being more recent. The media loves sensationalizing any numbers which always winds up trivializing the real science. Knowing all of this why would the USDA want to make a political statement based on such a short term and limited temperature measurements?

Originally Posted by GraniteStater

While it is definitely true that temperatures are rapidly warming in most areas, the USDA plant hardiness zones don't accurately depict microclimates, account for heat islands, and other factors. What about an extreme cold snap with temperatures 10-15F lower than the coldest hardiness zone range a location supposedly belongs in, even with the warming? It seems to me that extremes of all types will become more common. Some locations have low temperatures that are highly variable depending on the winter. In NH, the coldest it has been this winter has been -7F while a few years ago it was -24F. I don't know how an accurate zone can be determined when the coldest temperature each winter can vary by 15-20F in some locations?

All climate research models indicate more drastic changes in weather patterns. There can be more extreme cold as well as much warmer temperatures as any overall climate changes take place. It's one of the reasons "global warming" is no longer used to describe the probable changes. Reading about the map making process lets one see they made every effort to take into account local topography/geography, even urban heat islands, and they increased the numbers of places temperatures were recorded. There will always be small areas with big differences that will be missed. Both maps are composed of average lows, occasional outliers cannot be included as an "average". It is a reference for average cold winters so that people know generally what plants will survive and which ones will almost never make it. It isn't possible to reflect both unusual lows and averages in one map so it cannot be "accurate" for extremes. There was an extremely low temperature recorded in my area a few decades back of -24F. If they had used that as the number to base the map on I would only plant plants that could survive in what is labeled zone 4 right now on the map. I'd be missing out on the many plants that do grow here in a zone 7 about 99.9% of the time. If I followed this "accurate map" I could wind up losing half of those plants to the heat because they cannot survive the heat of this zone. Hardly something useful then, is it? Expecting it to reflect uncommon record cold would make the map useless for what its true purpose is: an excellent tool for telling you the kinds of plants that can be planted and survive in your area.

Originally Posted by Bulldogdad

The reason the USDA steered clear of the obvious political debate is because the data for the new map only encompasses a brief time span. And dosen't take into account any factors other than recorded temperatures.

Exactly.... just less verbose.

SCGranny that was the flip side of the increased numbers of places they have recorded temperatures from. There were places not accurately represented because they were extrapolated from data nearby that wound up being different once they were really recorded. I'm sure most of your plants won't know the difference if they've made it so far.