On my previous layout, I glued everything down including ground foam. On my current layout, I tried something new, for me anyway.
I was sprinkled some ground foam (Woodland Scenics Coarse Turf) on the layout when I accidently got it in an area I didn’t want it. I assumed I could just give it a quick brush with my fingers to clear it away. I soon found that it held on a lot better than I thought and I had to get the vacuum to pick it up. I realized then that I might be able to put it where I wanted it and press it down lightly to fix it in place. I tried it and was surprised at how well it worked. It stays in place very well and looks natural. Just don’t press it down too hard or you’ll tend to flatten it out too much. The best thing is that if you decide you don’t like the look or if you want to change it at some time later on, you can vacuum it up. I was concerned at first about not being able to clean up dust, but this really hasn’t been a problem. I can’t say that I’d recommend this for areas at the front edge of the layout or too close to track, but for all other areas it works well. You can try a small area for yourself. If you decide the technique isn’t for you, just grab the vacuum.