Is there any material that grass would grow through that would keep dirt inside? Cloth, a mesh screen, etc?

Most gardening centres sell landscape fabric, but grass probably wouldn't grow through it. It will keep dirt contained though so you could cut a hole where the grass needs to grow through. Does that make sense? What are you trying to accomplish?

I remember doing something in girl scouts where we cut off the toe of pantyhose, filled it with some seed, stuffed it with cotten, and then watered it and it grew (and we drew silly faces, of course!). but I'm not sure if it was grass or somethign slightly different. also, if you're doing a big project and/or a lot of them, pantyhose probably wouldn't work so well.

about a very porous material like cheesecloth?

I'm going to try the pantihose.

we did that pantyhose thing in elementary school.

we stuffed the pantyhose with soil and sewed it up so it looked like a head. decorated a face. and the grass was the hair.

kinda like a knock off chia pet

in my head, i'm imagining you building a giant really shallow box and filling it with dirt and grass to mount on a wall, hence the needing dirt to not fall out. i don't know if that's what you're really doing, but it would be pretty cool!

i think that if you use something like mesh/screen (such as for screen doors) that would work well. or even chicken wire, the kind with the 1/4 inch grid, would work well. but with something "wider" or "bigger" like that, the trick would be to keep the dirt flat until the grass has grown enough to really integrate into the soil and create a network of roots (like how sod can be lifted without all the dirt falling off). but once your grass is up and running and there's some sort of mesh keeping it in place, i'd say you're good. :)

post pictures of whatever it is you're doing when it's done!

I'm kind of doing something like that, but on a smaller scale. I'm still trying to construct it in my head.

You should try to make you hang-on-the-wall garden easy to put up and take down. Because you are going to want to water it while it's laying flat.

Let us know how this project turned out...I'm very curious!