Green roofs

Grow some House leeks to protect your shed from lightning.
As for construction, no idea but it needs to be strong to carry the weight of wet soil and plants.
A friend down west covered his leanto roof with plants and it looked fantastic but he needed a ladder for maintenance and weeding out the stray plants that grew there from seeds dropped by birds.

Goggle found this https://www.turfonline.co.uk/blog/top-te...of-plants/

That’s a great link thank you 

If done properly they are good insulation. I have a white roof at present, with over six inches of snow falling last night.

Ha ha glad I don’t live anywhere that cold   . I’m off to play in the sunshine