The black bugs were probably aphids, which can be very problematic with fresh new spring growth on JM's. And the stunted, wilty looking leaves would seem to support that supposition. Other than that, the tree looks fine. I'd be inclined to just stop messing with it and let it be :-) Pretty hard to develop a noticeable root rot in just 2 weeks..........

Yes, they are aphids but I've neve seen a plant deteriorate so fast with aphids, and I have seen plants deteriorate real fast with wet roots. Good to know that can't cause rot in such a short period.

I didn't mess with it but nursed it back to life. That's why it looks fine now.

I purchased a much smaller Japanese Princess recently by mail order. Some of its leaves burned soon after I planted it. I suspect it was because I didn't acclimate it to the light slowly enough, or maybe it was just the stress of being replanted. It looks much better now. Your plant looks healthy to me. I think the most important thing for you to do is make sure the ground stays moist but not overly wet. If you don't have one of those moisture meter probes you can stick in the dirt to view its moistness, I highly recommend getting one. They are cheap insurance.

Thanks for you reply MT. I know what you mean, I bought a small Orange Dream maple and it got nothing but burned leaf after I planted it. But it is known for that, whereas the Little Princess doesn't seem to have a tendency to get burnt leaves.

In fact my Little Princess looks beautiful now, growing new leaf and all, no pests. I want to put it back in the ground but I still worry that something might be wrong with its former location. But yes, it is more likely that I overwatered it and the soil clogged up. I am just not used to loam.

I like this plant so much. Every time I look at it I am amazed by its delicacy and color. It would really be a bad thing if I replanted it and it died. But I will have to just risk it, and take better care this time.

Here is a picture of my Japanese princess taken today:

And here is how I planted it. The soil here is alkaline clay loam, so it took some work. After removing the grass, I added dirt from another area to raise the level slightly above the surrounding area. I did not add anything to make the soil more porous at that point, but I did mix in some sulfur to acidify the soil and then squashed it flat . Then I created a wide mound on top of that using a mix of good store-bought topsoil, clay turf dressing AKA Turface, fine sifted pine bark pieces, some black compost, and a tiny bit of sulfur. After planting the tree in this porous mix, I formed a saucer shaped circle around the plant to keep the water from running off and mulched it with bigger bark pieces.