If you use green manure (fresh) you should wait 6 months before planting as it can burn the roots. I would not use peat moss anywhere, ground pinebark fines (usually sold as soil conditioner) is a far better soil amendment. Clay, peat moss and sand sounds alot like a recipe for bricks (watch the movie Moses and notice what he's stomping around in). I have some Kerria, Oakleaf hydrangea, anise, camelia, acuba, Mahonia, and leatherleaf Viburnum amongst others, growing in the well shaded portion of my garden. I also like Lenten roses (hellebores), Jeffersonia, carex, green & gold, soloman's seal, blanda anemones, lily of the valley, lungwort, woodland poppies, cyclamen, japaneese peonies, huechera and tiarrella, virginia bluebells, jack in the pulpits, etc. Just some ideas, Good luck!

Thank you Dieter. I can purchase topsoil for a little over $20 a cubic yard and 'super soil' (topsoil with decomposed mushrooms) for $10 more a cubic yard. Is that what I should go with?

I find that the topsoil you get in bulk has enough organic material in it to do well. I second the recommendation to not use peat. If you use sand, I wouldn't use much and builder's coarse sand is much better than play sand.

And yes, you can buy bagged composted manure at home depot (and other places, I'm sure).

The one with the decomposed mushrooms sounds great.

Ferns are a must for the shade garden and add a lot of plant volume. Itea is a wonderful shade shrub.

Oh, it sounds so beautiful and I'm so envious. My beautiful shade garden that my deck looked out on was taken away by Hurricane Ivan and now after Hurricane Dennis my husband has convinced me that we really should take out all the tall oaks in my front yard too.

Anyway, my absolute favorite shade plant is variegated lacecap hydrangea. It's variegated leaves are striking in the shade and it's periwinkle blue lacecap flowers are so delicate looking. I also love oakleaf hydrangeas and camellias. Aspidistra or cast-iron plant (about 2' tall) has lovely green tropical looking foliage and tolerates dry shady conditions. I like to plant red spider lilies (lycoris radiata) with the aspidistra as background. Cinnamon ferns (also dry shade tolerant) and hosta mix well. Some things that do well for me in partial shade include The Fairy rose, wood sorrel, iris, common white yarrow, mums, daylilies, gardenia, Anthony Waterer spirea, Japanese maples, dogwoods, black elephant ears.

Another suggestion for partial shade is Algerian Ivy. If you can find it this time of the year, it's really lovely. Mine is verigated and some of the leaves are solid white! It's striking and it isn't invasive. It adds a nice low-lying texture. AND, it is a perennial in Zone 8!

One of the easiest and cheapest things to improve your soil is to start your own compost pile, once ready you have the best of all worlds.

I use alot of manure in my gardens. In my experience, horse manure is one of the very best soil conditioners for heavy clay soil. Dieter is right. Don't put fresh manure on your beds. When I get a load of it, I offload it from the trailer near the bed it is intended for. I lay down a few inches of it, then wet it down. Add another layer, and wet it down again, until the pile is built. If you have leaves or other compostables, add them to the layers too, but continue to moisten it. Let it sit for a couple of weeks. The pile will get hot enough that you can feel it with your hands. When it cools down, usually in a couple of weeks, move the pile over, doing the layer and water thing again. The heating up part is very important, for that kills the gazillions of pasture weed seeds that are inevitably in it. When the pile no longer looks like poop and stops heating up, it is ready to spread on your beds. The amount of time this takes depends on how fresh the manure was to begin with and how often you turn it. If you are building a new bed, till it in. If it's an established bed, lay about an inch of it over the entire area. Your plants will love you for the trouble.

You can certainly buy bagged manures too. I keep a few bags of the composted manure from Lowe's on hand all the time. Whenever I move, divide, or plant something, I work at least a half of a bag into the hole. It has already been composted and sterilized of weed seeds, so you can buy and use it on the same day.

I agree with Dieter that pinebark fines are wonderful, but I disagree that peat moss is not. Used in sufficient quantities, it is an excellent soil conditioner for clay and acidifies the soil too. If you are planting azaleas, rhododendrons, blueberries, or other acid lovers, peat is just what you need. However, you must mix it into the soil. If it is laid over the top, it will dry out and prevent rain from penetrating down to the roots of the plant. Peat's big drawback is its cost, so keep that in mind. Pinefines are less expensive.

I'm kinda surprised that some of those plants you've listed do well in your deep south location.