GARDEN - VERTICAL STRAWBERRY GROWER - I've had great luck with vermiculite. About $70 to fill it up. But if I had it to do over again, I'd use gutter foam. Find it at Home Depot. It's a foam about 4" thick and 6' long that people install in their house gutter to filter out debris.
13 Low-Cost Gardening Projects With PVC Pipes
13 Low-Cost Gardening Projects With PVC Pipes | Postris