soil bags are a good idea...
i used five gallon buckets for my outdoor grow last year. They dry out much faster, are way more noticable (even painted). Alot of people say they dig holes and put the buckets in the holes to make them less noticeable but where i live 3 feet down and it's clay.. The water just lingers in the hole and soaks into your bucket. I put out like a dozen five gallon buckets in the spring last year dug holes all around and put the buckets in them.. Came back like a week later to plant and at least half the holes i dig for the buckets were totally full of water. Needless to say i didnt use any of the holes. This year i'm digging holes and replacing the dirt w/ composted dirt. I'm digging holes that take about 15 gallons of soil and 5 gallons of mulch. Going two plant two per hole in hopes that i will end up w/ a female in most of my spots. Sorry for rambling i'm high i would mos def go for putting them in the ground tho