Larry Hodgson emailed in photos and a description of his internal vertical garden he built in his bathroom in Canada. The vertical garden is also featured on Garden Bytes.

Larry Hodgson, is a well-known garden writer, lecturer, and media personality. He is a regular contributor to gardening magazines like Horticulture, Harrowsmith, and Canadian Gardening.

First, the wall is made of waterproof wallboard, then coated in a second waterproof coating (you definitely don’t want any water leaking through).

The coating is black which by coincidence turns out to be a good choice, as that color is very unobtrusive in the finished wall.

At the base of the wall is a reservoir, made to measure for the purpose. It includes an overflow pipe/drain, a submersible pump, a water supply pipe attached to the house plumbing system and a valve with a float (much like in a toilet reservoir) so water is added automatically as needed. I drain the reservoir even few months to change the water as it gets quite hard over time.

A pipe rises from the pump to the top of the wall attaching into a horizontal PVC pipe (plugged at both ends) that runs across the top of the wall. Holes are drilled into the latter at a regular distance. I inserted directional drip emitters into the holes, pointed towards the wall. When the pump is turned on, water rises up the vertical pipe to the horizontal pipe, then is sprayed onto the wall via the drip emitters. I also used lengths of plastic paneling to hide the piper and emitters from view.

After the piping was installed, I covered the wall with sections of natural cork bark (available from pet shops and orchid suppliers), glued into place with dark brown silicone sealant (the usual clear sealant is not clear and will be visible). Since cork bark sections are not flat, but somewhat curved, it was easy to hide the up pipe undereath.

Holding the bark in place until the sealant dried enough to hold it was my one technical challenge: I at first used indigenous teenagers bribed with promises of pizza and allowed to play annoying heavy metal music, but they found even pizza and noise insufficiently motivational for not moving for 30 minutes at a time and soon abandoned, but I at least had the upper part of the wall covered by then. I eventually used objects of various sizes (yes, even including a mattress)  to lean against the cork. This was very slow going, as I could only place a few pieces of cork at a time. If I had to do it over, I’d try to find larger sections of bark. I suspect that sheets of bark might be available. I did not want to screw or nail the bark in place, fearing any drilling into the wall would lead to leaking.

Finally, the reservoir is covered with a grid and the grid covered with stones. When the water drips down over the cork on the wall, any surplus falls through the stones into the reservoir and is recycled.

I originally intended to have the wall dripping throughout the daylight hours, as it is very pleasant to watch (plants actually bob up and down, as during a rainstorm) and listen to, but unfortunately my pump is far noisier than I had hoped and became an annoyance. I now run the water twice a day for 1/2 hour each time, enough to keep the wall moist. Once a day or even once or twice a week might be enough: I’ve never bothered testing it.

I use high intensity fluorescent lighting as a source of light for plant growth. This would be less necessary if the wall were in a well-lit room, but my bathroom receives little natural light, being on the north side of the house under spruces. I considered adding a skylight, but judged the local climate inappropriate (4 months of deep snow each year and a fairly cloudy climate year round). Besides, electricity is abundant, cheap and fairly green (hydro electricity) where I live.

I’ve experimented will all sorts of plants, mostly natural epiphytes (plants that grow on tree trunks or branches in the wild), including ferns, aroids, gesneriads, hoyas, bromeliads, cactus and orchids. They are simply tacked onto the wall where they quickly take root. Most thrive. Those that don’t die and are replaced by those that do. Also, lots of spontaneous plants move in, mostly mosses and ferns: I don’t know if they were in the cork or floated in by spores.

The wall has been running for several years now (5?) and I’ve had no major problems. Splashing is one, caused mostly by water dripping from overhanging leaves: were I to do it over again, I’d make the reservoir wider to catch more of  this moisture. Otherwise we’ve learned to live with a bit of water dripping into the bathtub. I eventually plugged the drip emitter at the far end of the wall, as it was constantly splashing onto the floor. It turned out to be unnecessary anyway (enough water flows laterally, especially near the bottom of the wall, to reach the plants in that section).

Maintenance is minimal: occasionally the drip emitters clog up (just like they do in outdoor systems). I unscrew them and clean them, then put them back in place. I remove dead and yellowing leaves and cut back overly exuberant plants (some are quite aggressive). I used to fertilize, but no longer do: the wall produces copious amounts of organic matter and the plants don’t seem to need extra minerals.

There you go: my plant wall in a nutshell!