I'm planning to put in a bog garden using an old rubber pond liner. From some things I've read, I thought I would make it about 12" deep with an additional 3" of fill above the rim of the liner so it can drain. I would fill it with sand and peat because I want to have all carnivourous plants growing there, and apparently they like minimal or nonexistant nutrients in the soil. Here's my questions: 1. In our rainy climate (Gulf Islands) do I need to make additional drainage, like maybe slits in the bottom or sides of the liner? 2. My soil is very alkaline, so I wouldn't want to use any in the mix, but should I add some bought topsoil to the sand and peat? 3. Does any one have a bog thats not connected to a pond, or is growing hardy carnivorous plants and can give me some advise? :) Thanks!