I'm not sure I completely understand your uphill/downhill situation, but it sounds like you have it figured out. You want the tree to get water (may need a water collection mote if your on the side of a hill) but not to get drowned by your neighbor's runoff.

Your hole dimensions need to change. The depth should be no deeper than the rootball of the tree (maybe even barely less than that). You will need to judge the depth by the height of the rootball. The hole should be bowl shaped (not barrel shaped) with the top diameter at least twice the rootball diameter. The wider you make your planting hole the better off the tree will be. In clay soil, I would make the top diameter three to four times the diameter of the rootball.

If you are going to be planting on a berm taller than the rootball, rough up the top of the soil before adding the berm, but you won't need to dig down into the soil. Doing so can cause the tree to settle below the level you originally plant it and can present an unnecessary potential drainage problem in clay soil. If you have to dig down to get soil, at least firm the soil (but don't compact harder than the original soil) as you add it back to the hole.

While the 50/50 mix of native soil and peat may help your tree get off to a faster start, I'm not sure it will be the best choice long-term. I would mix in 30% peat at most.

I wouldn't use black plastic to sterilize the soil. You are going to be killing off the native soil's beneficial fungus and microorganism life. There are times that this treatment can be beneficial, but you haven't listed any justifying reason (soilborne disease known to be present, etc.)

By the way, where are you getting your trees from?

Clay + Gypsum = good soil

Sandsquid since you are brand new to the forum I would be remiss if I didn't inform you of The Middle Tennessee Plant Swap on October 20th. Check out our website at http://www.midtnplantswap.com/.

We have several members that come from your 4th Bluff City area. If you are interested...shoot me an email and I'll be more than happy to give tons of information and answer any questions that you may have.

Thanks, that all makes sense...

I'm just trying to get the roots up out of the clay-bowl as much as possible.

Every hole I dig and back-fill turns into Cream-Of-Memphis Soup every time it rains, for the first year till things settle back in and "firm back up."

I've gotten pretty good at figuring how tall of a mound to make to get everything to settle to just above grade after two or three years, which is my ultimate goal. But I have not dealt with trees, just plants.

It _seems_ that once roots get established and start punching into the clay, they are pretty happy.

I would like to ultimately be able to pull the raised beds off after two years and have just a small mound for the next few years. Then, as the roots take hold in the clay and the peat breaks down, the tree will hopefully be just above or at grade, and firmly rooted and "acclimated" into the hard-pan formed by the clay.

But this is really been trial and error and lots of dead plants in the beginning years.

I've been having great sucess with nursery stock from TyTy Nursery in GA.

http://www.tytyga.com/

They have very fair prices, and healthy stock, in my experince. Only problem is they have a $50.00 minimum order(before the 25% shipping charge) ... So, I've had to put-off some purchases and step up others to make the minimum.
But they will take a mixed order and ship based on best planitng times for the destination location (based their opinion.)

Not a big deal, really I've just donated lots of "extra" plants to the "community garden" I'm statring on the hill behind my church.

In DEC_2007, I'm expecting:
Plantation Sweet Pomegranate, (1-2 feet tall)
Black Tartarian Sweet Cherry, (1-2 feet tall)
Governor Wood Sweet Cherry (1-2 feet tall)
Baba Blackberry, (2 Years Old)
Fall Gold Raspberry, (2 Years Old)
Brandywine Purple Raspberry, (2 Years Old)
Dorman Red Raspberry (1 Year Old)

Expected in APR_2008:
TN Mountain Fig (3-4 feet tall)
Mystery X Fig (3-4 feet tall)

I _hope_ to make rooted cuttings availible for trade from the all my pruning offal ;-)

Did I mention how much I hate this memphis Clay!?!?!?!

BEWARE of TyTy!!!!

Check out this link on GW last year: http://forums.gardenweb.com/forums/load/south/msg031557199110.html

The Gypsum added to the clay will break it down and should give you the results you are looking for without going through the whole raised bed thing.

Maybe I was lucky, I had good results w/ my first order from them, but thanks for the heads-up.

If anything is rotten, I wil be sure to persue the issue.

Just as I guessed, TyTy.

I think you are the only person I have ever heard that had great sucess with TyTy. TyTy is the CREME DE LA CREME of nursery ripoffs. BEWARE BIG TIME!!!! I would sooner send my money to a blind PO box in Nigeria than send them a dime. They really do have the worst reputation of any nursery I am aware of in the entire world period. There are thousands of complaints about them on the internet, many many complaints here on Gardenweb, and I've read that they are currently under investigation by multiple government agencies for fraud.

I like the "Cream-Of-Memphis Soup" analogy (-:

I understand what you were saying about the soil settling, but you might want to be careful about trees doing this. You especially need to make sure that the top of the tree's rootball doesn't settle below the top of the soil level. It's generally recommended to place the bottom of the rootball on solid ground.

The gypsum is a great idea, but is not a substitute for raised beds. The gypsum will help the soil where it's applied but will not change the overall drainage problem. Gypsum will not eliminate the "clay bowl". It will only improve the clay soil inside the bowl. If applied over a large area on a slope, it might help some because drainage could occur through the improved soil on the downhill side of the planting hole, but this is a special case.