Changes in zone hardiness maps

[TundraKev]

Is our climate really changing? This has been kind of a hot topic for at least a year or more n the gardening community. I'm still kind of up in the air on this one. I know winters in MN have not been what I usually consider normal for a very good number of years. I honestly cannot remember the last time we even came close to a -20 F temp. That used to be expected for at least a week or so every winter. Now, if we have a few -8 or -10 nights during winter, that's considered cold. We are getting sooooo soft up here in Tundraland.

I think it is kind of interesting that some organizations are coming out with updated Zone Hardiness Maps. It looks like some folks believe there are changes occurring.

Here's one I recently came across from the Arborday Org.

http://www.arborday.org/media/zones.cfm

It's kind of cool because you can look up your zone by zipcode and also compare the changes to an older map.

In a way, these changes can be kind of deceptive since winter temps - whether they are high or low - are not the only factors influencing a particular plant's hardiness in your area. For example: Even though our winter temps haven't been bitterly cold, we also don't seem to get the snowcover we once did. In Mpls. we've gone from zone 4 to 5 and I've still been losing many more things in my garden than in the past. That snowcover was really important for protecting plants.

Anyway, thought some of you might be interested in the map.

[Piper]

I'm not buying it. Too few data points. They're comparing 2004 to 1990. Global weather patterns are inherently cyclical with long periods. That's not to say we aren't trending warmer, but I wouldn't accept that until I saw about 100 years of data. In fifteen more years we could easily be cooling off.

But for now, the cannas should be happy!

Julie

[TundraKev]

I agree with you Julie. About a year ago, I came across another revised map put out by the USDA. I just can't find the blasted thing now. Grrrrrrrrrrrrrrr!! The map was much more detailed than this one, but also made some interesting changes. I was also bumped up a zone on that map.

I hope the cannas do well this summer. Last year, it was just too cold and nothing did that great.



(see what I'm really trying to do here is create a lot of debate, controversy, strongly worded outbursts from folks - you know - lots of drama. That can be fun. )

[Piper]

Right now the cannas are all over my kitchen counter. I need to bag 'em and get 'em started. Don't know if I'm up for bringing them in over the winter. (You need to get a life, man!)

If they don't make it (the new map suggests they now have a better chance!), it will just leave room for the tall beareded iris I just ordered.

Julie
(thought the magazine article created plenty of debate, controversy and strongly worded outbursts. You, sir, are a glutton!)

[Orchidzrule]

Ah, the wonderful world of hardiness zones! Unlike Kev, *I* was recently bumped *down* a zone. I was in three, now in two. At any rate, does this mean I can no longer grow zone three plants in my gardn? I say hell no!

Actually, I often urge people to push the limits and plant Zone 4 HERBACIOUS perennials. By contrast, not woody ones. Herbacious perennials get covered by snow in my part of the world for months. If you desire, you can augment it by putting mulch down in the fall before the white stuff arrives. Woody plants are much harder to protect.

I keep hearing about global warming and other climate change. I can't say it seems much different. The winters sometimes seem a little warmer, but other times seem brutally cold! Actually, we've had some rather cold (even by our standards LOL) summers in recent years.

I was told the supposed reason for these changes are they are now taking other factors into account besides minimum winter temperatures. They include (but may not be limited to) humidity levels, average total precipitation and amount of snow cover.

Anyway, gardening is getting to be fun now--my scilla has been blooming for a couple of weeks now, there are buds on my tulips and the lilies look healthy. Both of the latter look better in cages--necessary to protect against the damn rabbits!

Cheers,

Rob

[TundraKev]

I keep hearing about global warming and other climate change. I can't say it seems much different. The winters sometimes seem a little warmer, but other times seem brutally cold! Actually, we've had some rather cold (even by our standards LOL) summers in recent years.

I was told the supposed reason for these changes are they are now taking other factors into account besides minimum winter temperatures. They include (but may not be limited to) humidity levels, average total precipitation and amount of snow cover.

Rob

Rob

I guess I would never use these hardiness maps as an indicator of global warming. You're right, more factors are being taken into consideration when they publish these things. Actually, I think the reason I got bumped up a zone was because they now recognize the heat island effect of living in a big city. I live smack right in the middle of Mpls and it's always warmer here than 10 miles out in the burbs.

The thing that is the hardest on my garden is the lack of snow cover in the winter now. I won't mulch for winter. I know I should, but I won't do it. Since my garden is SO full, I almost welcome some of the winter losses. It opens up some more room to try something else. I know, that's sick, but true.

Sue

That's really good info. I really don't think there is much debate in the majority of the scientific community anymore. The climate is changing and very fast. I would think if it were some sort of natural cycle it would have been more gradual. When you look at the huge changes that have occurred in the Arctic regions in just the last few decades, it gets very scary.

I think another thing people forget is that global warming does not mean that every place on earth is going to have warmer temps all the time. One of the biggest effects of this seemingly insignificant rise in the plant's temperature is the affect this has on weather patterns and the jet stream. Some areas may experience warmer winters or summers, but other places may actually get cooler. Areas that once had good rainfall may become very dry or just the opposite may occur. The norm is not the norm anymore.

Enough from me.

[Orchidzrule]

Rob

I guess I would never use these hardiness maps as an indicator of global warming. You're right, more factors are being taken into consideration when they publish these things. Actually, I think the reason I got bumped up a zone was because they now recognize the heat island effect of living in a big city. I live smack right in the middle of Mpls and it's always warmer here than 10 miles out in the burbs.

The thing that is the hardest on my garden is the lack of snow cover in the winter now. I won't mulch for winter. I know I should, but I won't do it. Since my garden is SO full, I almost welcome some of the winter losses. It opens up some more room to try something else. I know, that's sick, but true.


Enough from me.

Oh, Kev, I could never get enough of you!

Seriously, the point about heat islands created by cities is impressive. A good friend of mine is a fairly keen, albeit novice, gardener. He lives at the extreme NE corner of Winnipeg, whereas I live in the south part of the city, although not way out. He always seems to get colder overnight temperatures at his house than I get. He'll see heavier frost, and especially in early winter, more accumulation of the white crap in a snowfall than I see. I have another friend who lives right downtown and his apartment still has live impatiens after all mine have been killed by frost in fall.

I'm not sure, though, if hardiness zones take this into effect--these are more along the line of microclimates than real climate zones.

Cheers,

Rob

[TundraKev]

Rob

I think they do take the heat island thing into account if they are big enough. On one map I saw, the Twin Cities was very clearly designated as a zone 5. All the surrounding area was still a zone 4.

Microclimates are very cool and strange. I know I have them in my own yard, but I've never really taken the time to figure them all out. This year, two clematis tangutica next to my house didn't make it. A couple of others (same clematis) about 15 feet away and next to a fence came through just fine.

Tis all very strange.

[Piper]

Kev,

Would you consider the ones that didn't do well, 'micro-clematis'?

Julie

[TundraKev]

Nooooooooooo

Especially since they grew almost all the way to the top of my house last year. I have a 2 1/2 story house.