Tips for Cheap Moisture Liners?
When I took up gardening in June, I put a lot of effort into renovating a yard gone to weed. A lot of things worked out well, while some things could have been done better. One of the projects that could have been done better is a full-sun north bed along the back wall, home to Canna, Colocasia, and Musa Basjoo banana plants. Everything grew and did all right, but nothing truly exploded, and the maintenance/watering was a bit too much.
The soil is your standard Pinellas county fare - water-repellent sand that only works when you water it near-daily, along with the fact this back fence faces a 6-lane road/highway that provides a near constant breeze that helps suck water from the soil. Originally, I amended the soil with some cheap home depot brand 'manure/compost' for better water retention. Obviously I fertilized the bed fairly often. Overall, it wasn't bad, but it wasn't enough either.
I've been considering tearing up the bed and redoing it, laying down a liner 12-18" deep to retain moisture and help present almost bog-like conditions so these plants can really take off. Problem is, I'm dealing with about 300-400 sq ft (around 40' long by 8' deep). I'm not looking to create an actual bog, I just want to overly-amend my soil and implement some barrier to prevent the water from draining away.
Any suggestions for cheap water-retaining barriers that'll hold up for a few years? Pond liners would break the bank. Talking to a few non-gardening friends, the options thus far are shower curtains, visqueen, and garbage bags.
I'd love some advice or personal anecdotes.
I've included a few photos of what the bed looked like shortly after the intial planting 6 months ago (ignore the Firebush & Yucca cuttings). Long term, I'm hoping to create a huge tropical wall of plants, similar to Coopman Cay 2002 (Google it if you're not familiar, Boca Joe took the photos).
Any help would be greatly appreciated!