You'll smell root rot and see actual rot if it's present. It's just like rotten food. When the drainage is poor the hole needs to be dug larger and you should have a "drain" hole at the bottom of the hole. Typically folks fill a drain with rock. It should go below the hardpan of earth so the water has a place to go. Unless absolutely necessary, your soil should never be amended but there are circumstances where it should be amendment. Never use more than 1/3 amendment to your native soil. A good amendment is sold at home improvement stores and it's called something like "tree and shrub amendment." It has bark fines and peat moss, basically. You should be using a pick axe to do your plantings. Also, when your hole is opened up, you should drive the pick axe all around the sides of the planting hole creating "pockets" for the roots to go into. To drive thru the hard pan you may need more than a pick axe. I'll provide you with a link that will help you. Dax Here is a link that might be useful: Preparing Hardpan For Plantings

I was thinking maybe a mixed informal evergreen hedge would be smart too. Part of this gets a lot of water, but part of it is exposed to much more heat, wind, and less water..so it might be nice to pick and choose different things for each spot. I have never done this before. Can I just start with one end and kind of slowly work my way over, picking individual things for each spot?

You don't have to be afraid of bamboo :-) Many people are uninformed about this plant, have no idea about the many different varieties and that it comes in two forms - running (which can take over the planet and does need a containment system) and clumping. Clumping bamboo does not grow in the same manner as running bamboo and is very well behaved.......the clump just gradually increases in its spread over time like a large ornamental grass does. No travelling vast distances underground and popping up in your neighbor's garden!! Or under your foundation! It has zero invasive tendencies. And clumping bamboos tend to be some of the most cold hardy varieties, with several species rated for zone 5 gardens. They make excellent screening plants with a narrow profile and grow to height rapidly......much faster than a tree or shrub. Unfortunately, the best and most cold hardy varieties would prefer to be sited in more shade in more interior, continental locations, only tolerating a lot of sun here on the west coast. Not sure how well it would work in the OP's garden but it might be worth considering. Cold Hardy Clumping Bamboo The giant timber bamboo Flo referred to, Bambusa oldhamii, is a very popular form of clumping bamboo but it is restricted to warmer climates. But many of the Fargesia species referred to in my link will grow and thrive in cold winter climates, provided they are sited well and given the conditions they need.

"... Goldspire Ginkgo, very columnar variety that is yellow in the fall and should mature to 14' - 16 tall and 5' - 6' wide." Oooh ... I don't think that's gonna happen. It will become much larger. Whenever size information comes from selling sources, it's 100% of the time going to be wrong. And they're stating a size after only a few years of growth, where the tree will not stop. Figure at least double size of whatever you're told. A fat clump of lilac in the tree form sounds like a great solution to the back right bed. You need some groundcover there, too. consider lily of the valley (so long as there's shade.) It does great there. Gotta be some Hosta somewhere, too. And daylilies in the sun. (From DeKalb originally.)