Just don't do what I did. I listened to my college professor tell the class how he went over the hostas in the Fall with a riding lawn mower to cut down the plants and mulch them into the soil. Sounded good, so I tried it. A year later I started noticing signs of HVX on my hostas. I have tossed 5, but I think I have more that are infected.
I am, perhaps in the same place you are. I want to improve my soil, but I already have a bunch of plants in the ground. This Fall I plan to work horse manure into the soil in between my hostas. I have a weeding tool that is just great at loosening up the soil. If I was gung ho, I would apply manure over the entire garden this winter, and maybe scratch the surface of the soil with a roto tiller.

When you say you put chopped leaves ON the beds, do you mean on top without digging them in? I think you need to get that mulch and other good compost in the ground at least 1 shovel depth to lighten up that clay. Always water a day or two before digging as it is much easier to incorporate.
Peggy

Do not incorporate the leaves into the soil until they have broken down or you'll have problems with drainage and with fertility.
I just throw compost around the hosta, without bothering to dig it in. I also let a very thick blanket of leaves cover them for the fall. I use those leaves during growing season as mulch.

I concur with Ninamarie!I do the same thing and my hostas do well.If your worried about getting them to deep, you can also use compost tea.I use it often and it is great, Judy

I'm not a great gardener, nor do I live in a wooded area. I do have clay soil. Almost nothing you do to the top will make a difference in the soil underneath. I've heard of doing those layering things, but somehow I don't think they are talking about "black gumbo" when they write them. You have to dig it up and mix something in to make it fertile enough to support what you want to grow there. (I use peat moss, compost and finely shredded pine bark (they might use something different in your area).) Then, you have to keep it up by adding compost and/or mulch on a regular basis.

Since you have a potential erosion problem, you might need to limit the amount of area where you want "beds" or improved soil or do just selected areas at a time. Maybe incorporate some walk areas that where the soil is not disturbed. Think about plants that will grow in unimproved soil. Here there's a fern that will grow anywhere. It's not evergreen, but spreads quickly. I think they call it a wood fern. You might have some kind of ivy in your area that would work. On our family cemetery, we've planted bearded irises to hold the soil in a shaded, unimproved soil that is subject to erosion.

Again, I don't think anything you put on top of clay will make much difference. It won't work its way into the clay. It will just get washed away or provide a very shallow layer of friable soil at the surface. The easiest way to improve clay soil that I've found is the "double-digging" method. (Google it.) Then, you incorporate your soil improvements as you go.

Just a couple of ideas.

bkay

Top dressing with compost worked on my clay but it took a loooooong time. Leaves will work great if you have worms to carry them down but I think the "water runs over the wooded area from lot run-off" may wash the leaves away before that happens. Short of digging the compost in, take a spading fork (potato fork) or other heavy tined fork, jab the soil and rock it back and forth to break it up a bit (if you can). Then top dress with compost. Any way to divert the run-off?

tj

This discussion is interesting to me. This spring I planted several new hosta. They have been doing nothing the whole time. the best I can say is they are still alive. I never plant anything here on my clay-gyp hill without improving the soil. This time I added good compost, well rotted manure, and leaf mold. the soil looked wonderful when I planted. Is it the weather? This has been the worst growing year I can remember in all my years(77). Started out with 80 degree days in Feb, then extreme cold in March. We had a little more winter moisture than usual. Very late spring, with good rains, unusual for us here. Extremely hot dry summer, with the exception of a 6.5" rain on the 4th of July. No moisture since, and my water bill is atrocious. Everyone here blames the weather for all gardening problems.

It has to be the weird weather. Everyone has had a bad year. It's been like a yo-yo here. Snow, cool, hot, dry, wet, hot, dry and hotter. I have a hardy hibiscus that is usually at least 4 ft. It's about 3 foot. It hasn't bloomed much either. I can't get enough water on it. Even my passionflowers are sparse. I would blame the weather. Hopefully, next year will be better.

bkay

Thank you for all your input - this year has been quite strange - 30+ days over 90 when 7 is the norm - little rain - plants burned to a literal crisp...I could go on but won't, it's TOO depressing!

I am thinking about digging up some of the hostas that continue to "just sit there" barely clinging to life - certainly not increasing in size - and putting them in different places, such as in my "stealth beds" the ones I make when my husband is at work, edged with the same stones so he might not notice that the beds are bigger!!! It has actually worked a couple of time!?!

I am beginning to think that as I age, and cope with a herniated back (I am better but have to be very careful what I do) trying to amend the clay-pack in the wooded area is going a step too far...Small oases of amended areas may be my best bet - seats and paths to enjoy the views and peace - and a less pressured attitude on my part.

Amending the ground may cause my hostas to start their search for light from a foot down - that's how much amendment I fear I'd have to put down!

Again - thanks everyone - I really appreciate your thoughts!

Jakki

I can't believe no one has mentioned two things... the fact that hostas will grow in clay soil and that its probably the trees starving the ground of water/nutrients... I deal with an acre yard shaded mostly with mature silver/water maples... I think I only have two other varieties of trees and ones a cherry I planted this year when my son was born.. I live in southern kentucky and my soil is also primarily red clay... Two things hurt clay soil... the fact that it holds too much moisture and that it compacts and hampers root growth...
I have compensated for this by amending with our "cattle- hay feeding- manure compost" that makes itself in the field where we feed the cattle...go to an old feeding spot about three years old and dig... it will be black loamy soil...then just apply a thin layer to the top of your beds... you may have to raise your plants....ride out in the countryside and stop by a farmers house... they're friendly people... and see if you can get permission to dig you up a few boxes of soil...
I also do not use any in ground fertilize close to the trees... If I have plantings close to the trees... I use something that can be applied foliar and high in phosphorus to help the plants roots compete better with the tree roots...We've just moved to our new home two years ago this november..so I've only had two gardening seasons... granted I moved a lot of mature plants into the garden... I really have impressed myself with what I've done in two years...
Basically what I'm getting at... is just alter your approach.. and lift your chin up a bit... I would say quit mulching or amending with anything thats not broken down yet... the breaking down process will cause you more fungus and rot than you are happy with....removing all leaf litter in the fall and mulching with a good mulch in the fall is a great gardening practice...definitely remove all old hosta leaf litter... water more often around your trees...check out www.pinestraw.com... you can order pinestraw in bulk shipped to your door... nothing else better to mulch with...slugs hate it....Good Luck... gardeing and nature is a challenge... especially here in Kentucky where the weather and seasons change daily... but the rewards are wonderful...
John