Chinese Elm despair! Help?

[miyagisan]

Okay, so I don't know why, but it's been well over a year now and I'm having the same problem with all of my Chinese Elms (one is pretty "old" - got it in Chinatown this spring - trunk over 1" thick, four 'starter' Elms purchased at Brooklyn Botanic Garden shop - exact same cultivar - bought this autumn).

Let me describe scenario so maybe that will help. Re-potted 'mamma Elm' right after purchase since it was in an impossibly tiny pot and had that heavy clay typical of Chinese imports. She did very, very well in her new bonsai medium mix all summer long. Did regular clip here, clip there to direct prolific shoots. Maybe I clipped too regularly (?) as all of a sudden, green leaves (not dry, not yellow, just perfect-looking leaves) started falling off. Then the new green branches started to wither and rot back. I chopped away, back to the old growth, and put it inside to imitate dormancy. Then, she began exploding with growth, so I got those baby ones I mentioned before. Everything's been going well in the well-drained, bug free-medium until just a few days ago. All of them are now doing the same thing!!! Dropping fresh, green leaves and then wilting back.

I've tried all I can think of before this happened to prevent it: a reduced watering schedule, proper fertilization... UGH! Any advice, help? It weird that I seem able to make the "most difficult" trees like Serissa and insanely difficult plants like rare carnivorous pitchers thrive, yet the so called "easy" Chinese elm is turning out to be the one plant I'm having terrible difficulties with.

Thank you so much for your advice!!

[iamurthman]

These easy Elms don't like sudden changes in environmental conditions. You mentioned water and feed, how's your ventilation? A blast of warm air from a heater vent or cold air from an open window or door can cause sudden leaf drop. Moving the tree from a shady to a well lit location or changing the air in your home (summer-air conditioner, winter-heater) can cause defoliation.

[miyagisan]

Good thoughts... hmm... I keep them all well-away from the doors and the radiators (I'm on Staten Island by NYC which is RRRREALLY cold right now). Could it be perhaps that the temperature in the house fluctuates (between 67F and 71F) up and down throughout the day like a yo-yo, as the drafts flow in and then the heat kicks on? Darned cheap landlord!!! I keep telling him to insulate! LOL They're over in the most stable corner under grow-lights... I've even considered making a mini indoor greenhouse with ventilation lol sigh

[miyagisan]

Hypothesis: I noticed that the 'mama Elm' is starting to flake bark off (I thought it was a big wound this summer - sweated big time lol) but now that a few other pieces have started to do the same, I am wondering if what I have is in fact the more "hardy" Lacebark Chinese Elm (Ulmus parvifolia) which fares best with a more temperate climate treatment. I thought it was one of those 'Southern China' ones since its bark was at first smooth and silvery. Could this be the cause? Perhaps this next year should I not treat it like a "outdoor only in late spring/summer" tree? I sure wish they could talk! "Hey, I'm going to be a lacebark, not a smoothbark!"

Picture of "Mamma Elm" this summer:

[miyagisan]

Here's the flaking bark taken just now

[miyagisan]

Whoops, trying to figure out this new Mac and how to make a picture smaller. Hope this works!

[miyagisan]

Adult 'Lacebark Chinese Elm' bark, courtesy Clemson University: http://www.clemson.edu/extension/hgic/tyk/2009/tyk01.html

[miyagisan]

From what I've read, the smooth-bark elms are more sub-tropical variegars and the rough, or lace-bark, should be treated as temperate (but not deep freezing of course) and allowed dormancy. Any other advice is highly appreciated, and I will try to make sure I keep them in as stable a place as possible.

Just an interesting tidbit - I ran across a full-grown one in Central Park, NYC! I was surprised it lived all the way up here, but I guess with a root system insulated by lots of soil it would fare better.

[miyagisan]

Update: I forgot I had yet another small Elm, all by itself in a separate little pot with a different soil medium mixture (I separated them all a few months ago to try different methods to determine possible solutions to this leaf-fall problem). Well, *this* one is just fine - in fact it's got the teeny tiniest little leaves (it's not even a Hokkaido!) that have slowly unfurled since its re-pot into this media. Any thoughts / feedback on this guy's growing media, i.e. do you spot something that makes you go *aha!*? Thanks for the advice! Mixture: 50% Porous red lava rock, 20% used 'activated charcoal' chips from my fish tank, 30% expanded shale. I'm venturing a guess at the activated charcoal??

[miyagisan]

Photo of the 'little guy', specimen in soil-less media including used aquarium activated charcoal. Sorry I have shaky hands lol - hard to see but the newest 3-4 leaves are hardening out at a size of 0.5cm!! The pre-repot leaves on there are about 1.5 cm. Things that make me go 'hmmm'!