Can older imported Chinese Elms be acclimated to Winterize in the colder zones?

I had a nice 25+ year old Chinese Elm which I bought online a few years ago. It arrived in Spring and I thought it would be able to aclimate itself to be able to survive a "typical" Zone 7 Winter. Much to my sadness, the tree died. I figured that it was because this was an older, imported Elm, probably from Southern China where these trees are subtropical or tender temperate at best. My lesson learned.
I now have another (imported 25yo) Elm which I "Winterize" for six weeks of "early Winter cold" it goes dormant (evidenced by the fact that it drops all of its leaves. It then starts putting out new growth within a few weeks of being brought indoors under flourescent lights), photo below.
My question is "Can this Elm acclimate itself to Winter outdoors for the entire season? Or, is it too old to change its ways? Any comments would be appreciated. Thanks!



FYI, I want to share this photo of an old Mulberry tree in Fredericksburg, VA on the campus of the local university. This is a treasured tree and the caretakers go to great lengths to maintain it.

I don't know the answer, but I'd doubt it. A tree's genetic background is going to determine its suitability to cold weather. If this tree is from a long line of trees that grew in semi-tropical China, it will have evolved out any cold-weather genes its line might once have had.

I know that an American red maple (Acer rubrum) that grew from seed in a Florida swamp will NOT do well if suddenly moved to a new home in the Mountains, 4 climate zones cooler -- even though the same species is common in the woods of the northern area. And northern trees don't do well in Florida summers, as I learned when I tried to bring several collected trees down from the West Virginia mountains. They died -- slowly, over the course of several years, but they died.

We warm-blooded creatures can adapt, but I'm not sure that a tree can.

Chinese elms grow naturally over a wide range, but move one specimen from south to north and I'm not sure it will survive.

BUt there's bound to be someone here that knows . . .

Thats some mullberry!

Thank you, Jim. I have also heard the same "said" about Bald Cypress. Sorry to hear about you losing trees, too. I will keep that in mind. I've heard about people refridgerating decidous trees (i.e. maples) in warm climates just to be able to enjoy growing them.
Todd

Jim Lewis explained it quite accurately and gave examples with other species. I have an Ulmus Parvaflora imported from South China(bare root) straight to Miami Tropical for about 2yrs with USA soil(no root nematodes apparent) then past 5yrs straight to Michigan where it has spent 365 days a year in a greenhouse(52 to 85 degrees) It drops many leaves twice per year(early spring-late fall) semi dormant about 2 weeks then immediately re-foliates. A friend of mine has had 2 of my other elms for past 12yrs but keeps them much cooler in winter(45-50 ish) and his trees have actual dormancy and one growing season per year. I claim no expertise on Chinese Elms. I have seen some with more serrated leaves and tighter internodes that may come from slightly cooler part of south China(elevation??) Dustin Mann

I only have two Chinese elms, and a couple of root cuttings as well as small air-cuttings from these two.

The first one is a "mallsai" about 15 cm high, it has spent several winters entirely outside, with temperatures staying below 0° Celsius for several days, sometimes as cold as -10° C.

The second one is a much bigger one that was obviously imported from China. It bought it at 50% off the price, in late December 2007. It had long pale green shoots since it had stayed for quite some time in the supermarket where I found it:



They both keep their leaves much longer than the other trees, some of the leaves at the tip of last year's growth are still green even after the very cold weather we had some time ago, but so far, they've survived.

I don't have photos after the snow, but here is what the big one looked like 3 weeks ago. I checked it again yesterday, and there are still some green leaves at the end of the branches:



But winters are probably not as cold as they are where you live, and temperatures drop gradually: maybe a sudden change is what weakens them, but here, but I know several people who have imported elms that stay outside in the winter with only very little protection if any at all, and have had no problem keeping them alive.

If the big one is dead in the spring, I'll change my mind and keep the pot

Thank you, Alain. I can see why you bought the tree; looks very nice; lots of branching to work with. The nebari looks great from your photos, too. I have a weakness for the two-toned Chinese pots. Please let me know of how it does this Winter. I have cuttings outside from my tree and will see if they made it through the Winter. Today, under a foot of snow and ice, the temperature reached 7 degrees F. Regards, Todd

Wow, that's about -14° C !

Until recently, I thought Virginia had a semi-tropical climate

I saw reports on TV about snow storm on the east part of the US, it seems you're having a hard winter there, even harder than we've had here...

Apparently Chinese Elms are widespread and are becoming a weed tree in many places. Regarding cold tolerance "In artificial freezing tests at the Morton Arboretum the LT50 (temp. at which 50% of tissues die) was found to be - 34 °C.

If you can find one that has grown in a zone with similar temperatures to your area, it is likely to survive anything that you throw at it. Doesn't help particularly with your imported tree, but at least you know that it can be done if you can source one more locally.