This is some flatwork we did with granite curbing. I'm debating on what I should use to fill the joints. This garden is supposed to have an old colonial feel. I'm leaning towards filling with topsoil and trying to get moss growing. Some of the larger gaps I may even plant thyme, jenny, or other "stepables". We used 3/8" stone for the bedding layer, so I think poly sand or even stone dust to some extent will continue to migrate into the bedding. Plus, they some of the gaps are pretty large, and the granite is at least 4" thick. Thoughts?