Living Walls and Their Precursors

by DIG-IT

Vertical walls, green walls, living walls – no matter the name – are the latest horticultural craze. Some surmise they may even be the next step in saving the planet.

The walls can be indoors or out, in high light or low, free-standing or affixed to a building or interior wall, have re-circulating water or not, support tropicals, sub-tropicals or cold hardy plants, epiphytes, terrestrials and veggies… er, edibles, and clean up water and air. Why not alpine and rock garden plants?

So many variables. What’s it all about? DIG IT! is curious. We will publish a short series on the many types of walls.

Our first story in this issue: Atlock Farm’s free-standing brick wall inside a greenhouse that has been supporting tropical epiphytes – orchids and bromeliads – for 15 years.

Low light tropicals and high light subtropicals have been decorating homes and cleaning indoor air since at least Victorian times. They came into fashion in the late 1970s and 1980s in the buildings of corporate America. Elaborate atrium plantings and smaller, but more scattered, office plantings were the expected, along with furniture and coffee service. The interior plantscape business boomed.

Saving floor space is not new. Plantings in work areas eventually streamlined into precursors of today’s vertical walls: window box-type planters filled with flowing pothos and hoya topped work stations; pots of philodendron on rows of file cabinets created green hedges along walls; and lipstick plants and a plethora of other beauties hung in brass bowls. All had virtually no foot print.

And, meanwhile, growers bred skinner dracaenas and tighter spathiphyllum that occupied a smaller foot print, yet retained a sturdy visage. And what about roof gardens and the Hanging Gardens of Babylon in 600BC?

But that’s not all. Everyone has known that plants clean air. NASA has done studies.

What’s new, I think, is creating an artificial substrate to grow plants vertically in an almost completely hydroponic way. (The only soil on the wall is the soil left on the roots of young plants when they are inserted into the wall’s medium, unless the wall is made by a backyard gardener with pockets of soil.)

Hydroponics and smaller foot prints do not negate the need for vigilant maintenance or the need for fertilizer, insecticides, biocides or lights, or fungus or bacteria killers. It may even enhance the need. In hostile interior environments, especially office buildings, it is war against mealy bugs, spider mites, scale and thrips – never mind mildew on cissus and sooty mold. Simply providing critical light and temperature to tropicals is challenging – so much so, that 3-year plant replacement costs have been historically built into maintenance fees. It is only the passionate (and naďve) plant lover-turned-business owner who looks upon growing plants commercially indoors with fervor and determination instead of viewing plants as disposable furniture.

That said, questions abound. We will try to answer them with pieces on:
• Interior walls with low-light tropicals and subtropicals
• Interior walls with high-light epiphytes-bromeliads and orchids
• Exterior walls with vegetables, herbs, hardy plants
• Walls with different kinds of substrates
• Walls with different ways of watering
• Walls as shields against temperature fluxes and other environmental parameters

Are vertical gardens the new magic elixir that will clean our air and clean our water enough to make a difference in life on Planet Earth? Are they the best way to grow low-light tropicals indoors? Or are they simply a fun, new art form with plants as a medium? Do thriving plants on multi-story outdoor walls confine their roots to the artificial substrate? Will they all be happy for years to come by being injected periodically with nutrients and washed with pesticides? What does the future hold?

Stay tuned.

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published February 08, 2011