Posted: 22/04/2014 at 12:43
Hi BM, unfortunately a combination of shade and damp means that limestone chippings will almost certainly go green, which is caused by a build-up of algae. Even on my south-facing well drained front garden, where they were sheltered from the worst of the rain by the house walls and eaves, my white Cotswold chippings eventually turned green after a few years.
I wonder if a different material would fare better? You can get shiny marble white chippings often called "polar white" which might be less porous, so would resist the algae taking hold? I've never use that though, so it's a bit of a guess.