One of the basic tenets of growing Earth-Kind roses is soil improvement using expanded shale. I purchase expanded shale at a nursery in my area, and I believe it works.
This company:
http://www.permatill.com/
has some good articles about ways to use expanded shale. I read through their website and found an article about how they are using it in NYC in soil to combat rats that burrow in soil around trees in public areas.
http://www.permatill.com/lands...
So it made me think maybe if this were tilled in with roses or hostas or anything else that voles eat, that it would protect the plant?
The article says rats do not like to burrow around the sharp pieces of rock. Makes sense to me that voles would not like that either. I don't have voles, knock on wood, but maybe some of you could try this?
I'm not promoting this particular company, as the expanded shale is manufactured by several companies and I would think brands are very similar. If I lived in the east coast, I would certainly buy from the company because they have done significant research on horticultural applications. It is promoted as an amendment for areas with heavy clay.
I started looking at places around here that carry it by the truckload. Chandler Materials in Tulsa has it. A pickup truck load dumped into your truck is about the same price as a big bag from the nursery. If it works for you, I would start googling manufacturers in your area and get it by the pickup load.
I can attest to effectiveness against drought. We've had extreme drought the past 3 years and I don't have irrigation. The roses in the bed where I used the shale look healthy. Of course, they are more hardy roses to begin with, but I'm talking about weeks of wind and 100 degree temps with no irrigation, and the roses look fresh.
Next I'm going to work it into the soil around my hydrangeas, hostas, hibiscus and anything else that needs more moisture. I don't have heavy clay, but this, (along with compost,) is a very effective cure for heavy soils.
