How can you construct a model of a green (vegated) roof?

Question

I am a 14 year old student working on a sciencefair project. I im 9th Grade Biology Honors. Our idea is to construct 3 different kinds of vegated roofs. We need to know what materials we should use and other details. Keep in mind, we are doing a science fair project. We need a small scale. We're not talking about an actual roof like on top of your house. We want to make a downsized roof model.

Thanks!

I am a 14 year old student working on a sciencefair project. I im 9th Grade Biology Honors. Our idea is to construct 3 different kinds of vegetated roofs. We need to know what materials we should use and other details. Keep in mind, we are doing a science fair project. We need a small scale. We're not talking about an actual roof like on top of your house. We want to make a downsized roof model.

Thanks!

Answer 1

If you are trying to keep scale, moss or chia pet stuff would give you a pair of appearances, while carefully growing grass so it was newly sprouted - thus thin and short - would give a grass representative.
I am not sure what you mean by 3 different kinds - lawn, bushes, and ground cover? Grass, food production and flowers?