In order to get that clay soil to do what you want it to do will call for three things; moisture, mulch, and organic matter. One way I would do the deed is to work the compost/humus into the soil, plant the plants, cover with the unfinished compost, give it some water, then apply a thick layer of mulch. Mulch will be the key as to how long the process takes, along with a healthy layer of organic matter underneath. It will take time, but the results are well worth the effort IMO...

Blutranes

Thanks for the advice. I have done a little more searching and some reading at the Va Tech extension site and lots of folks seem to advise NOT ammending the soil. I don't think I can do that. I just doesn't seem right. I think as a compromise, I will mix the clay from the hole with the compost/humus, dig the hole wide and shallow and then top-dress with compost and mulch on top. I know that this is a slow process to improve the soil, but I feel that I at least need to give these guys a fighting chance with the initial hole being ammended a bit

A lot of literature now says to not amend planting holes for trees and shrubs. On the flip side, I suppose extreme situations might call for extreme measures on occassion. Mulching is certainly a good idea regardless. I speculate that if you do want to dig in amendments then amending a much larger area might be the way to go (especially on the horizontal but maybe on the vertical as well) -- the thinking is that the feeder roots will want to stay only where the high quality area is so increase the area where the nutrition and the light soil is to get the roots to spread more. A completely different alternative is to find something else to plant that likes to live in your clay.

The problem with amending a planting hole in soil like that is that water easily flows into it, but can't easily flow out, so it creates what is sometimes called a bathtub effect. The water just sits in the amended hole and the tree essentially drowns. Also, the difference in the structure of the soil in the hole and the surrounding soil creates a barrier of sorts and the tree roots can't extend into the soil outside the hole, so the tree becomes root bound.

The larger the area you can amend, the better for the plants, as bob64 mentioned. To avoid the root conditions bpgreen mentions, be sure to dig the hole in a very shallow dish shape. As you move further out, even top dressing will help somewhat, if only to give the shallow roots somewhere to go. For the top dressing, anything organic will work, even leaves mixed with the clay (to hold them down) that you dug out.

tj

I would listen to your Va Extension Office . They have done research on soils in your area and know what works or doesn't . It would be a shame to see your investments slowly decline over time . Be careful when mulching too . Keep amendments away from the trunks - much farther away than you think .

What your extension people are telling you is to not just amend the planting hole for the reason stated by bpgreen. If you are going to amend the soil in the area where this shrub will be planted amend a very large area, or do not amend at all.

Ok, you have all convinced me. I am still going to compromise by mixing one 20lb bag of humus or compost with the clay soil I remove from both holes. This should be about a 2 or 3 to one ratio of clay to good stuff. Then I will topdress a pretty large area with what is left over. I know it is a long process, but any thoughts on how long it will take for the topdress to work its way into the soil? I guess it will at least help the first few inches in a season or so.

Thanks for all your input.
TBT

tbt3,

You wrote: "I am still going to compromise by mixing one 20lb bag of humus or compost with the clay soil I remove from both holes. This should be about a 2 or 3 to one ratio of clay to good stuff. Then I will topdress a pretty large area with what is left over."

Boy, you're a tough sell!

Stick with the Extension Service and the forum folks who support that advice.

And use all that compost as topdressing/mulch on the surface.

UNCLE! I submit. I guess it seems to be the prevailing theory not to ammend. I will top-dress very heavily then and hope for the best. I will trust the extension folks and the experts on this forum and hope for the best.

Thanks for the help and persistance,
TBT

Do you have to do the transplanting now? How about later in the year after you have done some overall soil improvement and the weather is not so hot and dessicating for your shrubs?

Here is the story... I got a buy one get one free coupon and bought some Hydrangeas. Too good a deal to resist--stupid me. I have been thinking of moving my Viburnum nudums to more sun anyway since they don't fruit well. Of course the best spot for the hydrangeas was where the Viburnum was, so voila! Now I am transplanting in order to plant. I know it's not ideal, but the temps will be a little lower this week and I have a soaker hose set up to keep them wet. Also, I thought they would survive better being moved now than trying to summer the hydrangeas in thier pot.
I'm hoping that I am being overprotective since they are natives and should do well about anywhere, but would rather do it right than have to start from scratch with new plants. I think it will be ok, but the clay soil is tough.

Thanks,
TBT

P.S. I just put them in and had to put in one small shovel full of compost (tell yourself that it was for the nutrients if that makes you feel better) in the hole and all the other organic stuff (bagged compost/humus, peat moss, a few coffee grounds, and mulch) all went on as top-dressing. I will try and remember to update as the summer goes on.