Angel325 thank you for the advice. Unfortunately, i couldn't save my plumeria. i kept cutting all rotten stems/branches off until one piece is left, but when i looked at it, it's brown inside instead of milky white. I don't know if i can still grow this plumeria with these brown looking martial inside or it's already dead. Where may i order another plumeria? It's sad b/c i was planting for my mom so i can give to her as a gift. the upload picture is the same plumeria i am planting for my mom. Any help to get the same flower...

Trim back the dead parts. Did you soak the bark before making the mix? The soil in the pot looks pretty dry. It also looks to be in full sun. It's best to keep it in shade until it shows some growth. Also many here are not fond of clay pots for citrus. But I'd leave it for now, it's best to not disturb it again. Next time you re-pot use a good quality plastic pot. Finally, one week is not enough time to show any kind of growth. More like a month is common. So make sure it does not dry out in that time, nor water too much. I know, fine line right? But that's what it takes.

Acer negundo, Box Elder, That explains a lot about what's happening. The ones around here in my town grow better from the ground than they do at the top. They sucker terribly and have dead branches or even dead sections of the entire tree. I've heard there are areas that they actually thrive with healthy looking growth but in general, all the ones I have see look awful by the time they are nearing maturity and are looked upon as a 'weed tree' around here. Buggy too and not long lived from what I've seen. They do grow fast so that's probably why it was chosen for your mothers wishes to see a tree mature but to tell you the truth, that tree isn't very big for as long as it have been in the ground so I think it must not like where it's planted. An area of rich moist soil would have produced a much better specimen. Really, I don't think there's much you can do to help that tree, just give it lots of water so no further damage is done.

To get back to the OP, here is my experience with amur seedlings. I dug several that were growing in a mulched bed at a commercial establishment and potted them. After a couple years they were single stem and a couple feet high. I planted them out in full sun and they branched from the base and became multi stemmed small trees after several years, on their own, with no help from me. In my case the tree did it's own thing, I believe it will do the same for you. So far as A amurense being a synonym for A tataricum, the few tataricums I've seen were single stem trees with larger foliage as opposed to amur's naturally multi stemmed wide spreading habit. Amur maple is used occasionally in mid TN as an ornamental, especially in commercial and municipal plantings. I sometimes see seedlings beneath the trees, same as I see seedlings beneath A palmatum.