Sedum green roof
At some point, once we've managed to lay our patio, we'll be building a shed/workshop. My partner reckons the pent roof is going to be about 20 square metres of area, possibly with a couple of skylight type windows. We'd really like to have a green roof on there and it seems sedum roofs are the most popular and the lightest type of plant to have on there. However it is so expensive to buy the blanket - £21 per metre squared is the lowest price I've found so far and that's not from my preferred shop. Then you've got the cost of all of the layers that go under the blanket, plus the edging to the roof etc.
I wondered if this is something anyone else has done and whether there are ways to save cost? I've found on Wiggly Wigglers they do a tray of wildflower plug plants for roofs that apparently cover an area of 20 square metres for £46. Although initially I thought it'd be great to have wildflowers I can imagine this might be trickier to install and maintain than a sedum blanket would be. I know I could then look in to buying sedum plug plants from somewhere but again I'm unsure whether this is a more risky set up than using the blanket.
Thanks for any help and advice,