In the rose greenhouse where I worked for a half-dozen years, we had a few odd plants. (. . . odd as in: not-roses

)
Some of those were hanging plants. They were potted and kept in a "rack" rain gutters attached to a north wall in one of the greenhouses. We did have a few retail customers and would sell some potted plants in the flower shop.
Fertilizing was with slow-release fertilizer in the potting soil. Watering amounted to putting a hose in the top gutter and turning it off when the lower gutter overflowed. Water dropped in pipes from one gutter to the next. Pipes were attached to the ends of the gutters, an inch or 2 above the bottom of the pots.
Fertilizer was injected into the irrigation water for the roses. They were in the ground but greenhouses built after I left used concrete trenches with peat - I'm not exactly sure how they were set up. For vertical growing I imagine that bricks of coco fiber might have strength sufficient to make things a little easier if you were using fertilizer injection irrigation.
For exterior building walls, I gotta wonder what Winter would bring. Not many plants can take much exposure of roots to severe cold.
Hattie, the British had glass greenhouses built against brick walls a hundred years ago or so. These were very narrow greenhouses and the walls held flues for moving air heated by a furnace. One can imagine that they were very efficient at capturing solar energy, as well.
I don't know how to go about finding a photo online. I remember seeing this in a book on the history of greenhouses.
Steve