They seedlings sound exciting and they could be a wonderful specimen in years to come. if you haven't done so already, I would suggest you gen up on training to make sure you catch things at the optimum time. Once that wisteria gets going .....
As you have full foligae on your Chinese Elm I am assuming you have it indoors, as mine sheds leaves in the autumn. All three of these species are hardy and as long as the pots don't freeze in the winter - we have a kind of staging in the garden with a covered top that we can drape fleece down from - they will be fine outside. If you end up with a lot of seedlings and young trees in training you might be very glad of this!!!! A monthly dose of cheshunt compund might well be helpful in keeping them healthy -- as you said, once roots have rotted it's a bit late
If you have time, perhaps you could put a photo of your Elm on to share- the more enthusiasts we can get the better!
Hope tis is helpful
