I want to build a garden over my front lawn that is basically just moss and clover but it has crocus' already planted that come up each spring. I was planning to put a load of topsoil on in a mound in the centre and just start planting as there is not much soil, just 6 inches enough for city regulations for planting a lawn. My question is regarding the crocus. They are well established and I really don't want to move them but I am wondering if they will still come up through the new garden or would that be too deep for them to come up through? really don't want to have to try and dig them all out of the lawn??? will they come up?