[quote]As winter retreats northward across the nation, gardeners are cleaning tools and turning attention to spring planting. But climate change is adding a new wrinkle, and now a standard reference – the U.S. Department of Agriculture's Plant Hardiness Zone Map – is about to make very clear how much rising temperatures have shifted planting zones northward.
The guide, last updated in 1990, shows where various species can be expected to thrive. A revision is expected sometime this year, and while the agency hasn't released details, horticulturalists and experts who have helped with the revision expect the new map to extend plants' northern ranges and paint a sharp picture of the continent's gradual warming over the past few decades. The new version will have a wide audience: the National Gardening Association estimates 82 million U.S. households do some form of gardening, a number expected to increase as more Americans plant vegetable gardens to cut food costs.[/quote]
Read the rest of the article; it's quite interesting about the problems with the current map, and what they plan to include in the new map.
The Arbor Day map changes are pretty unrealistic for my yard. I am most definitely NOT zone 6 as they show - still zone 5a. I wonder if there is a bit of propaganda wrapped up in this. I do not deny global warming, I just haven't seen that much of a change here.
Well Ladies I have to disagree with these maps, as I type it is in the low 40's at 5:45 April 7th
My old map says the last frost date for my area is March 15 but the last 3 years have seen frost at Easter.
I do agree there is a serious problem with global warming but I don't agree that it has been enough for zone changes...YET
Maybe day-to-day temperatures aren't showing a change, but plants and animals really are extending their ranges as a result of the warming trend. Loblolly pines are moving north, and so are pineborers. I've heard birders talk about other species, too, but I can't think of them off the top of my head.
[quote]Reclassifying a gardener's yard into a warmer area opens new options for planting flowers and shrubs . . . [/quote]
Not if the weather doesn't cooperate it doesn't. I've seen where some of these monitoring stations are. In parking lots. In cities. Next to AC exhaust vents. If I'm really interested in something, I'll try half a zone higher for an insignificant plant but I'm not putting the time, money and effort into planting a tree based on the new zones from the Arbor Day Foundation.
This winter was a good example. Plants that would have been OK the last three or more winters would have been wiped out this year. Before World War One my state was the second largest producer of peaches in the country after Georgia. That came to an abrupt end.
I'm not talking about day to day temperatures, we're farmers, we know what the weather is doing in our area and we definitely have not warmed up a zone. The frosts still happen in June and can start in late August. We were down in the -20s for a time this winter - it's snowing as I type and it is not an unusual occurrence, we regularly have snow the first week in April.
DAvid, LOL as if reclassifying it will really save your plants when it freezes!!
I have to say, I am in zone 4 and have been pushing it with plants from zone 5 and I agree that our winters are warmer than they were when I was a kid.
One day this winter was 22 below..That was the coldest, and the coldest in a long time, but I remember weeks below zero and often 20 to 30 below.
There certainly are microclimates all over the place with the mountains, so the average zone doesn't really apply up here. I'm just pleased to see the "official" recognition of what I've observed here.
I think the hardiness zone maps are based on average lows, not individual events. Before we can really move warmer zone plants into cooler zones, warming has to reach the point where the coldest events are a zone warmer than previously. Give it time, as I expect, perhaps, in our lifetimes, or for sure in our children's lifetimes, we will see the zones shift northwards two or maybe three zones. Reality is always much more surprising than theory.
Of course, that is if we can make it through the Solar Max in 2012. If not, things will REALLY warm up fast!
My observation in this area is that although some of the summer temps are higher than "normal", the winters are also colder than normal. A hard freeze is supposed to be a "100 year" event around here due to the ocean and bay influences on the weather.
The houses & barns etc aren't setup to deal with hard freezes, so now that they are happening, we're having pipe bursts and other related issues to deal with.
So I guess I'm saying that I agree with LariAnn's assessment that when the coldest events of the year are warmer, then they can consider shifting zones.
What I am mostly noticing is that we are having alternating periods of cold and warm that do not follow our usual seasonal patterns. This is causing a lot of confusion for the plants. They start to bud or bloom earlier and then get their buds or flowers frozen with the next cold snap.
While there may be some milder averages in winter in many years, it just ain't so Virginia that we are safely in a higher zone now. I had - 15° on one winter morning and that folks is enough to wipe out peach blooms nearly total.
G-M that's exactly what is happening here. For instance, there was no frost here from 3/2 while the average is 3/20. Sometimes there will be a killing frost in October when the average first frost is 11/21. Those are wide variations from norm and they'll often be a single short event just to mess everything up. All winter there were many periods lasting several days where people were running around in shorts and t shirts. I guess what I'm saying is that the seasons are blurred but with more extremes occurring. It's disconcerting to me, let alone the plants.
We decided to leave the garden frames up all year so that we can alternate between covering with a frost blanket or shade cloth to try to reduce the unseasonable temperature swings. That works for veggies, but fruit trees are another story.
Part of the differences are microclimates not captured by the maps, part of it is that we naturally go through temperature fluctuations. Given the cycles we have observed over centuries, we need periods longer than 20 years to base zone maps on.