How do you grow green walls and roofs?

Study their design, implementation and care with this informative course. Environmental scientists, urban planners, local government employees, architects, landscape architects, landscapers, garden designers and the backyard gardener will all benefit equally from learning ways in which we can create gardens that are functional in city scapes as well as other urban environments.
Green walls and roofs can improve aesthetics by hiding ugly views, or build beautiful garden spaces in confined areas, cool buildings and reduce glare, help to improve air quality in city environments, and give people the opportunity to grow food in the city.

Green Walls and Roofs are a Boom Sector in the Landscape Industry

  • A course for landscape professionals or property owners
  • Learn to create gardens in obscure places
  • Bring all the benefits of vegetation to built or polluted environments (improve air quality, aesthetics and modify temperature extremes)

Course Structure and Content
There are 9 lessons in this course:

1. Scope and Nature of Roof and Vertical Gardens
2. Construction Functional and Appropriate Vertical and Roof Gardens
3. Climbing Plants and Structures for climbing
4. Plants Suited to Roof and Vertical Gardens
5. Adaptations for Other Plants in Roof and Vertical Gardens
6. Container Growing
7. Maintenance –watering, pest control
8. Applications/Landscaping –Roof Gardens
9. Applications/Landscaping –Vertical gardens

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Lesson Aims:

  • Discuss the nature and scope of vertical gardens and roof gardens in horticulture today.
  • Explain engineering considerations involved with the building of vertical and roof gardens, both on small and large scale projects.
  • Select appropriate materials and plan the way in which the non living components of the garden is created, in order to achieve an appropriate and sustainable installation.
  • Select appropriate climbing plants for creating vertical or roof gardens, and determine appropriate strategies to cultivate those plants, in a variety if different situations.
  • Select appropriate plants for use in vertical or roof gardens, which are tolerant of the adverse growing conditions, having natural adaptations to growing under conditions that are encountered in these gardens.
  • Select and plan the cultivation of plants that lack natural adaptations to growing on roofs or vertical gardens; but which are none the less required to grow in these adverse conditions
  • Explain a range of container growing techniques, in a range of different roof and vertical gardens, that may be used with a selection of different types of plants.
  • Identify and evaluate problems with vertical and roof gardens, and compare options for solving those problems
  • Plan the development of roof gardens for both small and large scale applications.
  • Plan the development of vertical gardens for both small and large scale applications.

Course Duration
  100 hours

Why Create Green Walls or Roof Gardens?

Green Walls and Roof Gardens provide us with ways of bringing the benefits of a garden to a place where you might not normally think of creating a garden. In doing so, it can bring a whole range of environmental benefits to a place where often the environment might be less than desirable.

The choice of construction materials and method of construction for green walls and roof gardens will be governed by the existing architecture, specifications of the client(s), building code restrictions, loads and stresses on the building, as well as the availability and cost of materials and labour. 

Green walls and roof gardens which have been incorporated into the building design for new buildings will not face the same potential restrictions as choice of materials, construction technique and potential loads would already be factored in.   

Building a Green Roof
A typical green roof is created by installing a series of layers over the top of an existing roof. The layers from bottom up might include:

Insulation board – sitting on top of metal roof decking
A roofing membrane over the top of the insulation
A drainage core above the roof membrane
Plants in growing media above all of this.

The combined weight of the components, when they are saturated with water (e.g. after rain), must be adequately supported by the roof, with no leakage into the building below.

Building a Green Wall
A typical green wall could have the following components:

A vertical support structure – such as a metal frame attached to a wall
A series of pots or planters which can be attached to the structure
An irrigation system that delivers water to each of the container plants.

The combined weight of the system, when all the plants have grown and potting media is wet, needs to be supported adequately by the structure. Taller green walls can have a greater weight, create greater stress, and require more support from the structure than a lower wall of the same width.

Reasons to Grow Plants on a Green Wall

  • Can create visual interest on a barren wall or steep slope
  • Can provide a place to grow some herbs and vegetables and tiny fruiting plants such as strawberries on a vertical space
  • Can provide a growing space where non was available before for edible plants, ornamental plants, medicinal plants
  • A vertical focal point for a large auditorium, conference centre, office block or hotel foyer. It may extend several floors of the building
  • A place for insects, butterflies, birds to nest and live
  • Green growth adds humidity, shades walls and can reduce temperatures in the area
  • Vertical walls close to buildings can substantially reduce heating and cooling costs
  • A wall of oxygenating, air purifying plants is created
  • Interior green walls can be used to enhance the appearance of bars, restaurants, etc. 
  • Can break up the monotony of an urban landscape

From a horticultural perspective, plants that are growing in a vertical garden need well-developed support systems in place to ensure they grow healthily and safely. As they are at, or often above, the height of people they can pose a danger from falling plants, materials, or structures associated with the vertical wall. Debris falling from green walls which are several storeys high poses an even greater risk to human health since it will reach a higher velocity