NEW USDA HARDINESS MAP!

[moriphen]

So I am now Zone 7b with winter lows between 5ºF and 10ºF officially one of the warmest areas in my state. Lets get talking about climate change

http://planthardiness.ars.usda.gov/PHZMWeb/Default.aspx

M

[foxd]

Lets get talking about climate change

We've moved to a solid Zone 6a, but I suspect we are easily 6b. I've talked to people who would not believe in Global Warming even if the Earth was developing a climate like Venus. BTW, lets use the phrase "Global Warming" instead of "Climate Change". "Climate Change" was a phrase that Frank Luntz pushed to downplay the dangers of Global Warming.

[moriphen]

So I am now Zone 7b with winter lows between 5ºF and 10ºF officially one of the warmest areas in my state. Lets get talking about climate change

http://planthardiness.ars.usda.gov/PHZMWeb/Default.aspx

M

Giving the map a thorough look over, I can see that zone 8a temperatures are only 170 miles south of me on the Delmarva Peninsula. I think its safe to assume within 5-10 years will see 8a winters in my immediate area.

M

[foxd]

Considering how much the climate has changed in recent years, our Zone may be warmer than shown based on the Average Annual Extreme Minimum Temperature 1976-2005 shown on the map. I know that when we first began growing Phyllostachys aureosulcata, 16 feet tall was the tallest we could expect it to grow in our climate. It now grows 30 feet tall. There may be a new record this Spring.

[Iowaboo]

I didn't notice any difference for my area.

[Squishee]

I'm in Oakville, Ontario and it seems like I'm a zone 6a.

I'm actually pretty impressed with all my species this year. So far without too much snow and a lot of cold nights, my Spectabilis, Atrovaginata, and Bissetii have been doing pretty well; very slight leaf burn at the tips of the leaves without any cover at all.

[Paul Ont]

I wish they extended the map into Canada (I know USda, not agCAN)... There is a map for Canada, but it uses different criteria than the US map which leads to a lot of confusion and 'zone-inflation' among Canadian gardeners. Squishee- I'd say that depending on where you are in Oakville, you may now be borderline 6b. However, if you're away from the water it would be 6a! Pearson airport is now even a zone 6, upgraded from 5b a few years back.

[Rufledt]

I'm still borderline 6/7 and my parents are still 5a/b. No change for me in zones.

I wonder, if they do those charts by averages, would this super warm winter skew the next chart they do?

[foxd]

I wonder, if they do those charts by averages, would this super warm winter skew the next chart they do?

Considering that since the seventies each decade has been warmer than the decade before it and the fact that they use the average of several decades to figure the zones, I would expect it to result in the map being more accurate since it would then tend to reflect more recent temperatures.

[needmore]

But an unusually cold winter low next year will negate any impact from this one.

[stevelau1911]

http://planthardiness.ars.usda.gov/PHZMWeb/Default.aspx

I checked out this map again, and it seems like the entire map got a bit warmer so they seem to be updating it each year. It used to put me at zone 6a, but now it is saying zone 6b. I've also noticed that the climate zones in an area tend to follow the elevation more than anything else. Of course bodies of water help as well, but people living in higher elevations seem to be out of luck unless the entire region happens to be warm enough.

This kind of makes sense as temperatures do get cooler the higher you go. For example, the outside temperature of an airplane in the middle of its flight tends to be well below 0F. Sometimes -60F or colder.

[johnw]

But an unusually cold winter low next year will negate any impact from this one.

Precisely, I think they're getting a bit reckless issuing new maps so frequently. These maps are better done after several decades are under the belt. The thing with global warming is the erratic nature of the beast. It is not that long ago - 1992/93 - that we had one of the worst winters ever here,a winter like no one had ever seen in memeory - started the last week of January and continued non-stop into mid April. I think the rest of the continent had a similar one the year before or after that one.

The last one issued in Canada a few years back was complete chaos for the lower mainland of BC. In NS it seemed to be based on whether you could grow sweet peppers on the southern tip here - not - because the monkey puzzles were shading them out.

[foxd]

They may be issuing new maps more often, but they are still based on averaging several decades of data.

The problem is that Global Warming adds a trend line on top of that average, so that we may actually be in warmer growing Zone than the Hardiness map is showing.

True, if we got an exeptionally cold Winter it would cancel out the effects of the exeptionally warm Winter we had last year, but how likely is it we will get a Winter that exceptionally cold? My bets are that we will see another exceptionally warm Winter again in the next few years.

[jd.]

I didn't notice any difference for my area.

Nothing new here either. The winter lows these last couple years fit perfectly.
Except for last winter.

The last one issued in Canada a few years back was complete chaos for the lower mainland of BC.

The chaos due to elevation variation and mountain microclimates?
Or something more?

[foxd]

I didn't notice any difference for my area.

Nothing new here either. The winter lows these last couple years fit perfectly.
Except for last winter.

It doesn't take much much of a change in average lows to shift the Hardiness Zones. One would tend to think we have the same climate as the county south of us, but the county south of us has native stands of Rivercane and Maypop vine is native. I have also watched S.y.'Kimmei' survive the Winter year after year without top kill.

Last Winter we didn't even get down into the single digits. This year we are on track to have the warmest year on record, beating out 1998.