Inspired by Frits I bought some static model grass off ebay and tried it out on an old print from the shelf.
First I tried to use automotive spray glue, the kind you use when applying fabric to doors and such, but it was way, way to gooey and made a mess of the model. Since I didn't have any other spray glue, I tried applying a layer of clear spray paint and poured the grass over it. It stuck surprisingly well! I applied another layer of spray on top of the grass and poured even more grass over it, thus leaving it pretty well covered.
Here are a few pictures.
For a first test I'm very satisfied. It will be interesting to see how well it holds up, but it didn't fall off when touching, and the spray made it pretty static leaving an interesting looking effect.
The problem with a model this detailed is all the fine details is gone, this could be due to me applying several layers.
I will try with some landscape model printed in green plastic, to see how well it looks then.
Edit: I just tried rubbing it a bit, and it turned out most of the grass held on by surface tension. So the details wasn't that washed out, but also it was not very well covered after all, and not handling safe in that state.
Thanks for reading!