"global warming" can we add 1/2 a zone ?

can we now be comfortable growing zone 4a plants in zone "3b" or 6a in zone 5b ?
are the polar bears really suffering from lack of ice ? maybe a more serious question
, is the global warming a problem ?

The discussion of whether global warming is a problem or not is probably not an appropriate topic here given the ban on political/current events talk. As far as zones--there is a new proposed USDA map which I don't believe has become official yet, but on it many areas are now classified as about a half zone higher than they had been before. People have posted somewhere on DG before about it, so if you search for those threads you'll probably run across a link to the new map. So you can probably start experimenting with things that used to not quite be hardy, but be prepared that you may get a cold snap some winter that will zap them, I don't know that they would reliably be hardy 100% of the time, if you're looking for that amount of safety you're still better off planting things that are hardy a zone or two colder than you.

Ecrane3? Are you positive that this topic is off limits? I think that global warming would probably be ok as a topic, providing the discussion was limited to how global warming affects plants & gardening, (& not politics). I know I find it pertinent. I'm growing passion fruits now, when they never survived the winters here, before. Also, a lot of my plants of European origins, are succumbing to heat stress, and I'm having to replace them with either local varieties, or heat resistant ones....
Are you sure this subject is not appropriate? We could all use tips on how to make garden adjustments to our warmer climate, no?
Cyra

I was commenting on the parts about "is global warming a problem", and "are the polar bears suffering from lack of ice". Discussions along those lines I think could very quickly cross the line into politics/current events which are not allowed, not to mention causing tempers to flare since there are multiple viewpoints out there and everyone vehemently believes that they're right and think that people who feel differently are idiots (this holds true for a lot of things relating to politics or current events, that's why I think they're not allowed here!)

But if you've noticed that temperatures your summers are warmer than they used to be and it's causing problems in your garden so you want advice on how to help your plants deal with the heat and things like that, then that's perfectly appropriate.

Here's the National Arbor Day Foundation climate change map:

And here's one that focuses on the Washington DC area specifically:

I see what you mean, ecrane3. (And ty for the map, jkom51!)

Jim,
I don't know. If you are just going by coldest winter temperature then those numbers haven't changed. You might be able to argue that the lack of insulating snow would hurt warmer plants as much as the temps.

Al

Hedge your bets and punt plants with names like 'Blizzard', 'Snow Queen', and 'Glacier'.

Invest in 'Southern Gentleman', 'Rhett Butler', 'Scarlett O'Hara', and 'Zydeco Twist'.

Plant what ever you want and report to us the effect. We all want to know about Global changes. We in Montana are loving it. Many zone 5 and some zone 6 plants are thriving (until the next winter). We still have cold as we did before but we now have warmer days than we ever had much earlier. So you have to plan on plants that can survive the cold but need more warmer day. IE annuals.

One man's (or woman's) annual is another's perennial. Some gaillardia, lantana, and I'm sure there're more I just can't think of right now, fall into this gray area. I even had a late-planted pansy survive this last winter, and it's still blooming, but no long heat wave yet.

i think i have lost plants more to drought than cold temperatures. catnip is
supposedly hardy to zone 3 but rarely is it perrenial for us. In a local
store they have redbud which is not or was not hardy below zone 4b, and
hybrid tea roses which would have to be covered to survive. jim

when we go to Morton Arboretum , or "commune with the natural world" , I
feel we have nothing to fear and from that point are able to make good
choices in our lives, to help others and live at peace. If anyone gets a
chance to take the tram tour at Morton Arboretum to see the beautiful
tree forms from near perfect tree care, they may experience something
beyond words. The cicadas are humming loudly , flying madly , lilacs are
perfuming the air. Jim