How can I improve my soil drainage in my tree holes?

I have got a lot of tree I want to plant but I have a problem with really bad drainage in my heavy clay soil. I dig the holes 8 inches wide by 3 foot deep. I dug 5 holes, filled them with water and they took at least a week to soak away. Is they anything I can do or add to help drainage ?

Greetings, Just read your post. Yes, you can. Drilling or digging holes around the area you intend to plant the trees, you must, in your case, mound where you plant the tree, planting the tree on the mound. If you aren't at the bottom of a mud flat, if it is downhill in any direction from where you plant the trees you can: trench or drill a line of holes, breaking the wall between the holes, and fill the trench or bore line with sand, gravel or rock. Just like a, well, French Drain.

If you are at the bottom of the mudflat, you might dig a pond, running these trenches to the pond or hole. You can use this water to water areas that are not saturated or let you ducks decide what to do with it.

Go out and sit where in the area, with a cup of coffee, you'll be able to see what has to be done.

At our lower ranch we have clay, it's great keeps the water longer. I use a power auger to drill holes that I than fill with horse feathers, dried horse droppings, and mix the horse feathers with mineral earth in the hole as i plant the tree. I've moved trees that I have planted as I have said and the earth where I've done that is wonderful, it looks good and smells good.

Ive heard people say: if you have clay where you live, Move, but I have found it to be great. The more clay you have, the different mix you would use, you know, sand, raised rows or beds. If you have areas with silt, you can mix that into the clay.

Good luck, have fun.

I have found both in GA and in CA on clay that the best plan is to mound up, if necessary making a small raised bed with some logs or rocks around the plant, so that at least some of the roots on the plant are ABOVE the original soil grade. These mounds can be of amended soil, although most resources nowadays recommend AGAINST strong fertilizers, manures, etc. at planting time right near the roots. These can be applied off to the side or later as a topdressing. What you don't want is a deep hole filled with loose, amended soil. Water will accumulate in the increased pore space in there and not be able to drain off into the surrounding tight clay, leading quickly to root death from waterlogging. Only wetland tolerant plants can put up with this for long.
This is more of a problem in the growing season than in the dormant season, and is worse for newly-planted and young trees. As they establish and the mounds settle back toward original grade it becomes less of a problem.

hugelmounds. You need to take care that the fill soil still has a lot of clay so it re-bonds with the undisturbed soil so you don't rootbound your trees.

Again I say, IT DEPENDS. What I mean is, you have to look at your climate, and other circumstances. I don't know your situation, but I have found that in cold climates, the smaller mounds freeze sooner and more solidly than flat ground, so make sure the trees are well adapted to your climate.

But I agree, large mounds, or raised areas, or terraces, where excess water might be able to drain off, can be helpful to alleviate poor drainage. Or maybe digging a swale below the tree planting area, so the excess water can drain away from the trees. I know that is the opposite from dry country advice, but might be worth a try. I have found that if I dig a LARGE hole and score the sides of the hole so roots can get out --corners instead of a round hole helps too. I also have seen advice to NOT amend the hole, but just to loosen the same dirt and put it back in, then add amendments on top, and maybe in post-holes near the edge to encourage roots to go further. "dig a $5 hole for a $1 plant" so there is plenty of loose soil for the roots to spread.

i am thinking of puting yabbies in the bottom of the holes for a few weeks before i fill the holes with soil. first i will half fill the hole with water, then put the yabbies in the hole, as the water level goes the yabbies will dig deep down(i hope). yabbie means destructor.