Ulmus parvifolia perhaps fares better in milder climates. Where you live, the temperatures rarely go below 0° C if I'm right.
Almost correct
@AlainK Nights in winter regularly get down the -3C and occasionally -5C most winters, rarely a few deg lower. 9C below freezing is a record cold here.
I have seen some growers from much colder places saying that Chinese elm can be affected by colder temps. Does this mean that Zelkova is more cold tolerant?
I have also wondered if the problems of lack of ramification, long internodes, etc with my Zelkova might be related to the variety or provenance.
I see many great zelkova bonsai so I know it must be possible but nothing I've tried has worked with the trees I have which obviously leaves a negative impression. All my plants are descended from a single seedling I grew so maybe there are strains that are better for bonsai? Maybe it is just that I am not doing it right?