There is a great variance in resistance to frost in ulmus parvi. First bonsai was killed that way. I made enough cuttings by that time. Placed them in the ground. One out of ten survived winters, but died back every year. We've all been there, don't we.
ive heard a few folks say that, i have a few chinese elms, both cork bark and the normal, they all seem to do ok, ive not noticed much die back, maybe a few branches here n there but nothing to be alarmed about. i think they are hardy trees and adapt quite well.
these have been in the ground a couple years
two years ago, went in like this
IMG_2477 by
Bobby Lane, on Flickr
and was dug up in spring recently
you can see the significant amount of growth its put on in two years and the bark is becoming nice n craggy
20170330_135225 by
Bobby Lane, on Flickr
20170330_140107 by
Bobby Lane, on Flickr
pruned and went back in like this, there is a thread on its progression in the elm section
20170330_150413 by
Bobby Lane, on Flickr
this one also is being developed in the ground
IMAG3517 by
Bobby Lane, on Flickr
i recently took the wire off and decided to put it back in the ground after sorting its roots out it went in with padded root mass containing bonsai soil and went on a tile
IMG_3973 by
Bobby Lane, on Flickr
i have weed matting and bark mulch in my growing bed, might help protect them from frost a bit. i currently have 7 chinese elms in the allottment beds, so if conars interested he could have another look in spring when i might be looking to offload more
i have this other thats been in the ground a couple years, i wanted to pass it on but it was a matter of transport, but i dug it up and put it in plastic pot, it just sat there neglected so now its back in the ground
although it doesnt look like this now, it just needs a pruning and some wire. then the rest of them have just become bushes. just dont have enough space on my balcony. this was from a starter tree id got on kaizen for £25.
this is how it looked when i got it
not bad for a 'starter' elm