For vertical garden-building advice, we talked to Philip Yates
of the Singer Hill Café in Oregon City,
Ore., founder of website The Vertical Garden Institute.Yates says he learned through a lot of trial
and error, and also used the book The Vertical Garden by
Patrick Blanc, a botanist considered the inventor of vertical gardens, as a guide.
Start by choosing a wall. “If you’ve got a wall that’s ugly, that’s the one you’re going to want to do,” Yates says. The good news is that almost any wall will do, and unless you want to build a very large vertical garden or plant trees, you don’t need to worry about weight load.
What plants you should choose will depend upon the wall you pick and how much sunlight it receives. However, if you’d like to try particular plants, then choose a wall that will provide the best growing conditions for them.
Build a Frame
The basic structure of a vertical garden
wall is a three-layer sandwich made of frame, plastic sheeting, and fabric. Build the whole setup before hanging it. While you can actually attach it directly to a wall, Yates says, building a frame to hang on the wall means taking it down will be much easier.
Yates uses 3/4-inch PVC pipe, elbows, and four-way joints to build a frame. He advises against using metal (because of the additional weight and expense) and wood (it requires pressure-treating to protect against moisture rot—you don’t want water trapped between a wood wall and the frame’s plastic).
Attach Plastic Sheeting
Attach a sheet of plastic to the frame. The plastic acts as a backing for the fabric layer, plus keeps the water off the wall. Yates uses expanded PVC sheets. (Note: If you want to try this on a wood wall, you’ll need to ventilate behind.)
Attach the Fabric
Attach the layer of fabric to the frame. This is the material in which your plants will live, and which will hold water for them. Yates has used basic felt carpet padding, but he says that you can use just about anything that will retain water without rotting.
You’ll need two layers of fabric at least. Attach them directly to the frame with galvanized screws and stainless-steel staples as if you were stretching canvas across a frame. As long as the fabric is secure and taut, with no buckling or wrinkles, you’re good to go. “You just need to attach it some way so it doesn’t come off and it looks pretty,” Yates says.
Set Up the Irrigation System
To keep plants growing on a vertical surface, you’ll need an irrigation system that can provide moisture throughout the fabric layer. You can make one out of poly tubing with fittings that lock (Yates uses Perma-Loc irrigation fittings). It’s basically a tube across the top of your panel with emitters that drip water down. Your best bet is to get them from an irrigation supplier.
You can buy a standard valve and irrigation drippers, but you’ll need a propagation timer that can be set for seconds rather than minutes. You want a quick flow of water for 10 to 15 seconds from three to six times a day, depending on weather conditions and your particular setup. Attach an emitter every 2 to 3 inches along the top irrigation tube and experiment to find the right balance between keeping the wall wet while not overwatering the plants.
Attach the frame to the wall using stainless-steel hardware (to avoid rusting). Hooks are fine if you think you’ll want to remove the frame; otherwise, brackets screwed into the wall and the frame will also work.
Add Fertilizer Injector and Attach Irrigation System to Water Source
To fertilize your wall, attach a fertilizer injector, such as Add-It,with a simple irrigation valve that sends liquid fertilizer into the irrigation system. Then hook up the irrigation system and connect to your water source. You’ll need to filter the water with an irrigation water filter, which is cheap and available at most hardware stores.
Remember, there will be some runoff; one way to deal with it is by planting a flower bed underneath your vertical garden.
Choose Your Plants
As with any gardening, take into account sun, shade, humidity, wind, and cold when choosing plants that you’re going to leave outside all year. If you intend to leave the garden out during the winter, Yates recommends selecting plants for a colder zone than the one you live in. For example, Oregon City is a zone 9, but Yates plants at least a 6, and usually in the 3 to 5 range.
If you’re building a detachable wall and planting it with evergreens, you could try storing it in a cool, dry place for the winter while the plants are dormant.
Some plants that have done well in Yates’s walls are hostas, iberis, phlox, ferns, weigela, and even blueberries. “Native plants seem to do better than nonnative,” he says.
To insert plants into the outer layer of fabric, use a razorblade to make a horizontal cut in the material. Get as much soil off the plant’s root ball as possible (to help stave off root rot), and insert it into a cut. Using a staple gun, insert three to five stainless-steel staples to attach the cloth to the plastic backing in a semicircle around the root ball, creating a secure envelope.
The fun part, Yates says, is designing your plantings, and the height of a vertical garden offers lots of possibilities.
Choose plants that will grow 2 to 3 feet out from the wall, and plant them at the top so they create shade underneath. If you do this, though, keep in mind you’ll have to plant shade-tolerant species underneath, such as ferns. Also, a plant that’s 8 feet off the ground will often droop, Yates says. That gives a nice waterfall effect but also smothers whatever’s underneath, so you’ll have to trim it back.
Planting in vertical strips, with green shade plants in one strip and sun-loving flowers in another, is a good idea. “If you’re going to do this and have the most dramatic effect, and want your friends’ and neighbors’ jaws [to] drop, you need to get above their heads,” Yates says. “They need to look up at a plant they’d normally see at their feet.”