I'd till it in - at least 6". And you might want to add a soil conditioner, like vermiculite, while you're at it - so it will be less likely to compact again in the future. It's a lot of work, but worth it - the beds I've treated that way grow SO much better.

Good luck!

You could work some in around the outer edges of the plants and put the rest on top and let the worms move it down. It takes longer, but works.

Mary, since your plants are already established....I honestly think that you should keep applying a good organic mulch and/or compost once or twice a year. The soil critters, especially the worms, will make sure that it gets taken down into the soil. I have clay soil, too. I tilled some OM into the beds initially, but never again. However, I sure have to replenish the layer of mulch, lol.

If you do decide you just have to take on a major project, I'd suggest that you go for the compost as your only amendment...plenty of it.

I hope I doesn't sound silly or impertinent. Forgive me if I do, I just want to understand how this works. There must be some part I'm not getting. If I put the compost only on the surface how long would it take for the little worms (or whatever) to make the soil 1 feet plus below the surface aerated and loose so my perennial plant roots don't get compacted with the clay and difficult to lift out and divide in the meantime.

I understand how a forest works, but it took many years for it to turn from a meadow into a mature forest, and the soil to likewise change. You see I have a meadow next to my property, bordered by a forest and the soil in that meadow is like concrete when I try to stick a shovel in and add wildflowers, yet it has not been disturbed for 5 years. I suppose it is not a mature meadow ecosystem yet as enough organic matter has not accumulated. I assume most flower gardens are more like a altered meadow than a forest.

If I put down 6 inches would it be nice 1 plus feet down in 2 years, 4 years or does it work much quicker than that?

Mary

Well, whatever happens in the forest, I have beds to which I've added organic matter and mulch on top regularly, and beds where I've started over and tilled the stuff into the compacted clay. The ones where I did the tilling have much healthier plants - faster increase, and more bloom. The ones where I've added stuff on top have a nice layer on top - but down below it's still hard clay. When I dig in those beds I do find worms in the clay, but it's still clay!

I've been doing this for several years, and putting the compost on top of the soil doesn't do much. That's been my own personal experience. Mixing it into the soil around the plants would be much better. However, removing the plants and tilling it in, 6" deep like gdionelli said, will work the best. That's a lot of work though! Been there, done that. I'm glad other folks have had great results with laying the compost on top and letting the worms take it down, but that has not worked well for me, and like I said, I've been doing this for several years and tried several methods.

Deanna

Forgot to mention, it takes lots of compost to make a difference. If you till it in, you will need to till in 4-6 inches of compost. So it would be best to buy it in bulk, rather than by the bag. That's a lot of bags!

Deanna

Thank you everyone for your input. It's really nice to hear about the experience of others in similiar situations.

My husband and I figure we'll work in about 6 inches of compost. We did get that truckload delivered after all. Even if I don't get all the beds done, better a few done thoroughly this year.

To be honest some of the roots of my plants are so grass infested (congested with all that clay) that lifting them out and chopping out a clean piece seems to be a good idea. Just lots of work......so better start before I'm too old.

Mary

I've been working on some really clayey soil
and I've gotten the most change from tilling
in peat and adding gypsum dust. It always looks
good if I till something in, but the acid test is
how bad the surface forms a crust after rain.
Peat and Gypsum seem to have almost stopped this.
Compost alone adds organic matter, but it seems to
wash down into the soil leaving a clay layer on top.
(Rain sorts the particles.)

I don't think you can really ammend clay, just dilute
it. Where I live the best answer is a raised bed without
native soil in it. I'm using compost, vermiculite, and
peat in these in equal amounts.

I'm not sure if all of this is the best way to go, but
it's the best I've been able to determine by trying
various things.

Landrum

I'd dig it in, too. You don't have time to wait for the forest effect, obviously.

A little clay goes a heck of a long way though, and organic matter disappears as it breaks down. So I'd plan on adding MUCH more compost than I thought I needed, and I would prepare myself mentally to have to repeat the process every year.

(Where I live was a seabed, tens of thousands of years ago, and the soil is alkaline clay as a result. I tilled in organics for a few years but eventually gave up after seeing so little difference in soil structure, and went to 12 inch raised beds. These are filled almost exclusively with organic matter. It's lovely stuff to work in, and the underlying clay 12 inches down is still useful for holding water.)

"...and I would prepare myself mentally to have to repeat the process every year."

Certainly after digging the compost in the first year only a top dressing in succeeding years is all that's needed.

tj

Somebody suggested gypsum. Before buying any gypsum, find out what kind of clay you have. Gypsum only helps certain kinds of clay.

Every soil seems to be unique.

Top dressing wasn't enough for me. I had to dig in loads of compost every year - it just vanishes into the clay.

I lived in Wisconsin for a while, and gardened there, I never saw anything like the soil out here. I assume it comes from being at the bottom of the ocean for millenia upon millenia. Or some such.

The raised beds have solved the problem, but only because I don't actually garden into the clay much. In the very small areas that aren't raised beds, the soil still appears to be 98% clay when I turn it in the spring, despite massive organic amendments for years on end.

Your mileage may vary.

Some clays will not respond to just piling compost on the soil surface and those require some initial tilling in of the organic matter. Other clay soils will respond quite well to simply piling on the organic matter. Sodic clay soils may need gypsum to aid in clearing out the salts that accumulate in them, but for other, not sodic clays, this would be a waste of money because gypsum will do nothing for that clay soil.
How quickly organic matter wil lget worked into your soil will depend on how active your Soil Food Web is. A soil with very little activity by the SFW will take almost forever, it seems to us, to start working that organic matter into the soil, and those "dead" soils may also need initial tilling because the SFW will not develop in soils that do not have sufficient levels of humus.
So Mary what you may need to do is take you cultivator and scratch some compost in around your existing plants so your soils food web can start to develop so in the future it will digest and move down into that soil the mulch you plunk there. How many earthworms do you see in your soil? They are an indication of how healthy your soil is. Also the more earthworms you have in your soil the more moles you will have.

patty4150, yes I think that it is common for people who live in places where they actually have topsoil to have a hard time understanding SoCal clay. No-till folks have assumed that my soil must have been 'abused'. I say, no it just needs a few thousand more years to mellow.

On the other hand, I have a hard time understanding what rain must be like (grin).

Gary

Ahh, clay. I miss clay. I wish I had clay soil again.

I used to garden in adobe clay and I used to think it was the most miserable soil in the world. Literally, it is the stuff the Spanish built the missions out of. Not good for plants, I thought.

now I garden in glacial gravelly till. I miss clay. My soil will not hold water at all. Probably a good thing with the amount of rain we get here, but garden plants suffer in summer. No nutrient holding capacity either. Clay holds both water and nutrients. On the other hand I never see root rot here.

Gypsum only works on certain kinds of clay, as stated. It does NOT work on California's adobe clays, that's for sure. Nothing much does. Clay is clay and you can never change that. Part of the challenge of gardening, for me, is to learn to work with what nature gives me as far as soil and climate and water go.

Clay's moisture content needs to be just right for you to dig or till. Too dry is too hard to work, too wet is too heavy and you'll ruin the structure so it's even worse than it was before. I found it best in dry weather to water the soil 2-4 days before I planned on digging, and to not dig at all in wet weather.

Mushroom compost is great stuff. But, you will have to work it in somehow to get the most benefit, and then reapply annually at least. Organic matter works by being broken down, so it goes away and has to be replenished. It's food, and food disappears.

Adding things to clay in an attempt to make it into loam is futile. Clay dominates the soil. You'd have to get it down to about 20% clay to change the texture to something other than clay, and it's just not feasible to do that except in raised beds or mounds in small areas. The real concern for me would be, not how hard it is to dig up the perennials to divide them, but how well do they grow?

This thread continues to be interesting. How true that we don't really appreciate what we've got till we loose it.

Well we have begun to change the soil.

I suppose the problem I should have emphasized was getting out the weeds. That's what was really driving me crazy. Even now as we dig out clumps of perennials there seems to be no way to completely separate the weeds, apart from hours of hosing them down each perennial. Even chopping the perennials into smaller pieces doesn't help much. So they are getting some rough treatment.

But we have the best friends that helped out yesterday to remove stuff, move the path, and work in the compost. Then we put a layer of compost on top too. There must be at least 8 inches added total. OOOH what a lovely thing it is now. Still other large beds to do, but a good start.

I think my roses and clematis are singing!

Mary

Just a couple weeks ago, I got done amending clay for a garden. My area is aprox 20 x 40 feet and I added 6 yards of compost, tilled in well. What I now call dirt is so nice there it's unreal.

When I water the garden area in, the water just disappears into my new soil. If I water next to it (Clay with about an inch of top soil, the water till 1st sink as if it was taking it in then run off as if I had it cover with roof shingles.

Hi Mary,

I'm also in the Ottawa area, but in the west end - do you mind me asking how much that mountain cost? I'm considering it, but haven't called yet. Also, does that mean a full dumptruck?

Thanks,
Gail