The color of the clay gives an indication of the type of rocks that clay came from, but what all clays, and sands, need the most of is organic matter. Horse manure, or any other animal manure, is a small part of that need, vegetative waste is more important. Just like in a compost pile you can add 3 parts vegetative waste to 1 part animal manure because the nutrients in the animal manures are pretty water soluble and will be washed out of the soil much sooner if the vegetative waste is not also added to help stabilize them.

I use horse manure because I have sandy soil too. Horse manure will tighten the soil, so it would not be good for a clay soil. Not sure about how roses will do in the clay, but my guess is that good compost will certainly help.

So my clay comes from limestone. Makes sense and explains the color. Thanks, Kimmsr and Softmentor. The bed is done, and the rose is planted. I just have to drench with iron sulfate. I appreciate your helpful input. One interesting thing is that the ground isn't all clay. It's either spotty or in a pretty thin layer. At one point I thought it would be a plus if it held water like a bowl since the soil acts just like a sieve, but I don't think it's working that way. It seems having the chunks of clay in the bed will keep moisture around the rose - once they get good and wet - and that will be a plus. I'll just keep adding compost on top. I think it will be OK.

Thanks again!

Sherry

Clay soils tend to lock up both moisture and plant nutrients and organic matter slides between the clay soil particles so excess moisture can flow more easily and that organci matter changes the clay soil particles so the nutrients are not held so tightly. The single best thing to add to any soil is organic matter because in clay soils it wil ldo what is described above and in sand it will fil lin between the soil particles and hold both moisture and nutrients in the plant root zone.