I live in west central Georgia-Carroll County-and the biggest issue for me is water, the second soil quality, and the third ambrosia beetles.
During the years after I first planted my trees we had several summers of little to no rain. One summer we went almost two months without a drop. I’m convinced my trees would have died without a lot of supplemental water. Even so, many struggled. This year we had the wettest summer of the 23 I’ve lived in Carroll County. The trees thrived, continuing to put on new growth through August. I know you have cooler and perhaps wetter weather than me, but a drought the first or second year after you plant could be catastrophic, especially if you are growing in full sun.
Soil improvement has also greatly helped my trees, I believe. Lots of hard red clay here. Every year I’ve top-dressed with either 3-4 inches of woodchips or up to a foot of leaves. After 5 years, the soil finally is starting to look better. You probably have better soil than me, and of course I have no scientific evidence that this organic matter has made a difference, but the trees sure look healthier.
Ambrosia beetles have killed several of my young trees. They attacked some of my most vigorous growers. I recently saw a presentation arguing the beetles are only a problem for stressed trees, and had convincing data to back that up. All I can say is that my trees had done o.k. the prior year and appeared to be doing fine in the early spring. My guess is the trees’ roots were waterlogged because of the clay soil and wet winters. The biggest issue with these beetles is that once you see evidence of an attack, saving the tree is a real challenge, and impossible if a heavy attack. Again, you probably have a lot better drainage than I do so this may not be a problem for you. There are multiple ambrosia beetle threads on the forum, probably the most relevant is Ambrosia beetle on paw paw