Another vertical gardening idea
 

This person used reclaimed rain gutters for planting. Neat idea. I know a bunch of people who could use this technique to expand their plantable area.

DIY Vertical Garden with Reclaimed Gutters @greenUPGRADER

Are the gutters really deep enough to support optimal root hold? I can't imagine they would be, honestly. I can see drilling multiple holes in the gutters and leaving them suspended in a pool or something, though. The root structure can then grow in soil while being able to get a real hold on the gutter itself and drawing water from underneath.

Although, some plants don't like "wet feet", either.

Thats the samething I thought initially too. However, it seems to be working alright from the pictures.

Gutters would also be just the right size to use as a hanging box on deck hand-rails.

It would also work well on the exterior of second-story deck guard rails.