I found a site that sells the mats in the UK www.greenroof.co.uk that carries "Nature Mat", and I suppose this is what you are talking about. I would imagine you could make your own mats.

The various sites I have seen describe putting a frame around the roof to hold the soil. You need to waterproof the roof before adding the soil, or eventually your green roof will become your green floor! There are several different layers in the soil to allow drainage so your roof doesn't end up a big mud pie, also. I can't remember which magazine I saw an article in - Countryside, Backwoods Home,
Back Home, or Mother Earth News. You might try going to those sites and searching. Also try some straw bale sites. If you do any other searching, try "living roof", or "eco-roof" in addition to green roof.

If you can get your shed VERY sturdy and get the layers in place, I would imagine itwouldn't be too hard to grow your own mats. You could use something like muslin I guess. I would spread it on loose soil, top it with loose soil, and plant sedum seeds on top. When the roots come through, you can then move it to the roof. I would think, however, it would be easier just to plant the roof.

Last year I purchased packets of mixed ground cover sedum from Park's. There were 1000 seeds in each packet and I think they cost about $2.00.

If you do decide to do it, please let us know how it goes! I've wanted to do something similar, but I don't have a roof to use!

Kay

Kay-
Thank you for your ideas. I have not checked the magazines you mention. Good idea. I have checked out straw bale and green roof sites galore.

What sort of luck have you had with sedum germination? I was going to use plugs. I have always vegetatively propagated my sedums. Is it easy using seed?

Ginger