Vertical Gardens–on walls–provide insulating and beautifying greenery that can disguise the most uninspiring walls and serve as a delightful alternative to conventional fencing. ‘Living walls’ create privacy, sound barriers, habitat, moisture, and shade in addition to flowers, fruits, and vegetables. They naturally filter or evaporate rooftop runoff, taking a load off stormwater and wastewater systems, thus protecting rivers and streams.
Living walls differ from trellises and climbing plant-covered walls in that they feature a growing medium that allows plants to take root in the wall, not just at the base of it.
Garden walls are essentially gardens turned on end. San Francisco Bay-area garden-wall designer Ahmad Hassan shares his secrets for making garden walls, essentially a soil sandwich held up with welded wire.
1. Roll out 4-foot-high galvanized welded wire mesh such as that typically used to reinforce concrete. Spray paint it brown or dark green to blend in with the vegetation it will support. When dry, spread it with shredded redwood mulch and wet sphagnum moss for aesthetics.
2. Cover mesh with a layer of sod, then some soil with a high clay content to hold moisture.
3. Snake a soaker hose or drip-irrigation line through the top foot of the wall to provide water (may not be necessary in wet climates). Hassan prefers quarter-inch hose with emitters spaced twelve inches apart. An alternative is to install bubblers at the very top of the wall. The water will trickle down through the wall to the ground.
4. Tie the sod to the wire mesh, upholstery style, with zip ties.
5. Pick up the wall, stand it upright, and attach to posts firmly embedded in the ground with cement bases.
6. Attach the wall to the front of the posts, then add another sheet of wire mesh to the back, hiding the posts. Fill in the space between the wire mesh with mulch, sod, and soil.
7. Cut three-inch holes into the wire mesh and insert plants at least one foot apart.
Plants for the Garden Wall
• Many varieties of short-stemmed plants can be used; marguerite daisies, erigeron daisies, geraniums, rosemary, lavender, ivy, lantana, moss, vinca, or ice plants.
• For low-water varieties, choose succulents such as hens and chicks and sedums or fast-spreading ground covers such as creeping thyme and creeping jenny.
• Climbing vines such as the fast-growing white potato can be planted in the wall or in the ground in front of it and trained up the wall.