I’ve been doing some reading on vertical gardening (pic from http://www.lowimpactliving.com).
A few more links:
On a slightly more accessible scale: Gardening Australia’s Vertical Garden Fact Sheet
Instructables: Vertical Vegetables (good tip: Tomatoes don’t thive under these conditions. I remember reading something similar about the upside-down tomato planters available - yields are small, because tomatoes just don’t like growing that way.)
A PDF from Cityfarmer.org - Container & Vertical Gardening (Technology for the Poor)
Available on Amazon: Garden Up! Smart vertical gardening for small and large spaces (5 stars from 15 reviews)
And, there’s a variety of space-saving solutions at urbangardensolutions.wordpress.com
I’d like to try this at home, but the only surface that gets a lot of sun at the moment is the side fence between ours and the neighbour’s backyard, and I’m a bit worried that unless I waterproofed the apparatus somehow the water would damage it.