"As temperatures warm across America" - temperatures cannot warm, they are numbers, numbers cannot warm.

Here in our garden we have been able to harvest tomatoes and leave the plants uncovered at nights well up into September. Just a few years back we usually got a heavy frost towards the end of August.

I had lived in Oklahoma for many years, moved to the South, then moved back to OK. I missed lots of the beautiful plants I grew in the South, like gardenias and camellias. The first few winters in Oklahoma were so warm, I planted some gardenias and camellias. Ever since them the summers have been almost unbearable (30 days straight of over 100 degrees) and the winters are now brutal. Way more unpleasant than it was in 1973 when I moved here. The cold winters killed my Southern plants and the droughts and heat of summer hurts the rest. And, this week, the tornado sirens are going off daily.

No question about it, you can now grow stuff that used to be on the "not cold hardy" list. BUT. Do NOT make the naive mistake of thinking that "global warming" means- every year. It does NOT. What we are actually facing are greater extremes; in both directions. Here in Minnesota we've had record warm, and record cold winters - both - in the last 5 years. That will certainly continue; even as "average" temperatures continue to increase. But your lovely English Walnut tree- will grow beautifully for 6-10 years - and then be killed to the ground. That's not theoretical - it actual long experience with folks trying push boundaries.

Just noticed the very nice "Average Winter Lows" chart in the article. It illustrates the problem perfectly - I'm in Zone 4; 4a, to be exact. According to chart, I should have winter lows of -30 to -20. Actually. Until this past winter, we had gone about 6 years without even hitting -20. This winter? I got -41; twice, 6 days apart, quite unusual. I've experienced -40 here 3 times in 40 years. In one of those episodes, an official temp of -50 was recorded within 30 miles of me. Wiped out a bunch of trees, that one. IT'S THE EXTREMES. Not the averages. Ask the grape growers in upstate NY.

Ah yes; A climate change article about plants, and the biggest state in the union...gone!! but besides that, zones alone do not make for a good way to determine which plants will grow and survive. Snow cover, wind, aspect all join in. In Anchorage, we have had dramatic changes to our winters; fewer below 0 days , shorter winter season... but we still get the occasional late April or early May snow. In my garden alone, I have at least 3 zones; as does Anchorage proper. Study your garden, or site, and you will find better ( higher ) zones for your experimental plants.

It's not just the plants. I heard a meadow lark downtown last month, and we have had a mourning dove in a nearby tree for two years now. I have seen hummingbirds where we usually have eagle, hawks, and osprey. Something's up.

While the rest of California fries in the summer, we shiver in the fog out by the coast. It seems like the hotter it gets inland it gets colder by the bay.

And yet, in northern New England, due to the extended periods of severe cold this past winter, we have lost many plants that we were encouraged to try to 'test' the zones. I have been gardening for half a century and this zone warming is a reoccuring theme, one that has never yet actually happened. The pattern is a sudden colder winter, or one without enough snowcover, or one where the snow comes early before the ground freezes, or an early spring, or a late spring. In other words, no one knows and I no longer believe these forecasts. Truth is, there is no pattern, nor a dependable change in the zones.

Intriguing if only because we live in the most climate stable area in the US (the north woods of the midwest). Even so, we keep records of plant phenology, lake ice and bird migrations and have seen a lengthening on both ends but definitely lengthier falls.

In conversation with an arborist friend the other day, I commented that in order to escape our area's now 5 months of scorching weather that when I was a child was only August one needs to move 3 states northward. Not only do humans in our area not have 4 seasons anymore, nor do the trees, plants and animals.

It's already happened on the Olympic Peninsula. When I moved here 21 years ago, my planting zone was 7a. Now it's 8a. But who cares about my perennials? What matters is that our snowpack, source of the rivers that sustain the great rain forests of Olympic National Park, is at 20% of where it should be. The trees, many of them 300 years old, will not survive this. The salmon will die, as will the orcas that feed on them. It's happening now. Not in our children's and grandchildren's time. Now.

While trees certainly die all the time. I had a 70' tall 80 year old Scots Pine in my backyard that I had to fell last year because of fungus. A fungus which was likely brought over by birds from a pine grove about 350 yards away. 14 trees in that grove were also felled for the same reason. Though not really my fault, I felt a certain amount of failure for the tree's demise on my watch. That tree was planted about 27 years after my house was built and provide shade an ambiance for several generations of people in that house before we bought the place about 10 years ago. It will be interesting to see how much hotter our house gets this summer without it being there. On the plus side we now get enough sun light on the roof, that it is now a good candidate for solar panels. And the view of downtown and the mountains have definitely improved.

While it’s noticeable that winters are milder on average, those cold snaps of -25 degrees continue to occur here in New England making a mockery of any revisions of plant hardiness zones. Climate change isn’t just warming, but extreme weather, too.

I noted on a recent trip to Northern Louisiana -- where I grew up in the 1970s -- that there are now palms (fan palms and date palms) and palmettos in many neighborhoods. When I left my town in 1980 it had exactly one, shortish, palmetto, which was quite the novelty and owned by a local gardening enthusiast. It was encased in a small plastic greenhouse during especially cold weather, which occurred two or three times each winter. Looks like the area is clearly in Zone 9 now.

These 'forecast' are nothing more than wild guesses, and more often than not, wrong.