Green walls, aka. vertical gardens, living walls or green façades, are a marriage of function and aesthetic. They are usually striking, sometimes marvelous, and almost always very beautiful.
  
Green walls are commonly divided into two categories: green façades and living walls. With green façades, the plant roots are in the ground. Green façades can be fixed to a standing wall, or supported by a special support structure - a modular trellis system or cable and rope wire system - and they utilize climbing plants (which can grow directly on a wall without the help of a structure) and/or cascading ground covers.

The plant variety of a living wall can exceed that of a green façade, and as a result, they can require more advanced and regular maintenance. Living walls may also use a wall structure, though they are built out of connecting pre-vegetated panels or integrated fabric systems which can be attached to a standing wall. They are a combined system of polypropylene plastic containers, geotextiles, irrigation systems and a growing medium, all of which support the vegetation, which can include a wide variety of ground covers, ferns, low shrubs, perennial flowers and edible plants.

A green wall might look like it takes a lot of work, or perhaps even a team of professionals to keep it alive, however, once the green wall structure is installed and the vegetation is planted, green walls can be maintained by simple fertilization and watering; no weeding, cultivation, herbicides or heavy maintenance is required. 

Keeping in step with practical and ecologically sound planning, native plants and drought tolerant plants are considered great vegetation choices for green walls - native plants providing habitat restoration and a food source for local birds and butterflies, and drought tolerant plants conserving valuable water.

Green walls can even sustain vegetable growth, including the growing of lettuce, herbs, beets, tomatoes, strawberries, radishes & carrots.  

Green walls utilize soil, or a special inorganic growing medium which works with fertilizer, holds adequate water, and allows the roots to receive plenty of air. The growing medium is perfectly capable of sustaining hydroponics systems.  

In a living wall, the structuring panels are designed to allow water to flow internally from cell to cell within each panel, and subsequently from panel to panel. It's common for a drip irrigation line to be installed early on to provide the easiest and most effective method of watering possible.

There are many benefits to a green wall:

• It can provide sound insulation
• It can filter air particulates to improve air quality
• It can reduce the Heat Island Effect
• It can moderate a building's internal temperature via external shading
• It will create a microclimate, which will help to alter the climate of a city as a whole
• It can help a building retain heat otherwise lost to convection
• It provides storm water management, absorbing 45-75% of rainfall
• It acts as a natural water filter and water temperature moderator
• It provides biodiversity and a natural animal habitat
• It can be very beautiful and/or astonishing

Note: Ivy covered walls are not considered green walls. Ivy is an aggressive, self-clinging plant which grows without any assisted support and is known to damage walls and infringe upon the building's maintenance.

For further information and resources, visit the following sites:

• eltlivingwalls.com
• livingwallgardens.com
• eltgreenroofs.com
  
• @bdcnetwork.com, 6 Things You Need to Know About Green Walls
  
• Patrick Blanc, green wall designer
• @chemicallygreen.com, 10 Incredible Living Walls
  
• Living Wall, a Feasibility Study for the SLC