“How does a vertical garden work?”

There’s lots of sources on the Internet. Here’s a couple I thought were really useful:

How to Start a Vertical Garden

20 Vertical Gardening Ideas for Turning a Small Space into a Big Harvest

50 Vertical Garden Ideas That Will Change the Way You Think About Gardening

10 Most Inspiring Vertical gardens Ideas

And there’s a lot of really good information (and some great pictures like this one of the Green wall of the Simon Fraser University, Burnaby, British Columbia, Canada) at: Green wall - Wikipedia