Hello fellow Bonsai enthusiast :)

I am new to the Bonsai world and have decided to try out different methods of achieving this amazing art. My goal right now is to experiment with different propagation methods and see which type of plant works best for my climate. I've started by stratifying some cherry, pear, and maple tree seeds to be planted next month since they've been in the refrigerator almost three months now. I've also collected three baby elms in my backyard which are only about a foot and half tall and transplanted them into large containers which I'm now realizing I should have kept in the ground for training but its one of the many mistakes of a new comer I'm learning. I also found a couple of Elm seedlings so I have them growing in a container as well, and I put a couple of cuttings into the ground just to see if any take root (two have). Air layering is next on my list and I'm wondering if anyone has any tips or advice on air layering with Chinese Elms. This process sounds more complicated and I'm really unsure of the amount of moss to be wrapped and just how long to expect to wait for transplanting. Also, if anyone has any info on cuttings from the Chinese Elm would be helpful as well. Thank you in advance!