Types of green walls
At their most simple, green walls can just be a planting of wall shrubs and climbers. It’s hardly innovative, but claddings made from plants such as pyracantha or ceanothus can provide many of the benefits offered by more complex systems.
At the other extreme are engineered, planting systems. These often consist of modules fixed against a wall that contain soil or media for the plants to grow in. These often require irrigation systems and may need professional installation and maintenance.
Engineered green wall planting systems
Decide how you wish to plant your green wall. There are various systems available, according to the size of your wall and budget.
- The simplest way of greening walls is to plant climbers, wall shrubs or fruit trained as espaliers or fans
- With other systems, plants are set in cells containing compost or other growing media and connected to drip irrigation. Harvested rainwater can be used with some systems. These are installed by specialist companies
- Green walls can be installed indoors with additional artificial lighting
- For smaller budgets, there are simple grow-bag-type products for walls or you can plant up one or more small panels that can be added to, depending on space and budget. These are available from garden centres
- Introduce the plants at as small size as possible, ideally as plugs. Establishment is likely to be more successful at this stage of development
- If the wall you are about to add plants to receives less than half a day of sun in mid-summer, choose plants for shade
- To simplify planting and watering needs, try to choose plants that have similar light and moisture requirements to the conditions on offer
When to plant green walls
Spring is the best time to plant because plants are coming into active growth and will establish quickly.
Planting Green Roofs and Living Walls by N Dunnett & N Kingsbury (Timber Press, 2004 ISBN-9780881929119). This book is made available through the RHS Lindley Library.
There is a broad range of plants available to clothe walls, and includes the following:
- Climbers and wall shrubs are the simplest way of adding interest to walls. There will be a climber to suit your wall, whether in sun or shade
- In green wall systems, a range of herbaceous perennials, grasses, herbs, fruit and vegetables can be planted
- Plants for summer interest (sold as annuals, patio plants or bedding perform well and are widely available as plugs in spring. Alternatively, grow plants from seed. Experimentation with different plants is also worthwhile.
Vegetables and herbs
Tolerant of shade
Alpine strawberries, chard, chives, land cress, lambs lettuce, lettuce, parsley, rocket and strawberry ‘Mara des Bois’.
Strawberries: seed-raised everbearers (sometimes known as perpetual strawberries), such as ‘Aromel’, ‘Albion’ and ‘Mara des Bois’, oregano, thyme and shade tolerant fruit and vegetables with adequate irrigation.
Summer interest for walls
Flowering bedding plants tolerant of shade
Begonias and busy lizzies.
Bedding plants grown for their foliage
Ipomoea ‘Sweet Caroline’
Ipomoea Sweet Heart 'Purple'
Tradescantia ‘Purple Sabre’
Plants for summer interest – sunny
Begonia ‘Million Kisses Series’, Bidens ferulifolia, busy lizzie, ivy-leaved pelargoniums, petunias and verbena.
The following plants will thrive in sun too, as long as there is a good supply of water.
Ajuga reptens, often hardy Begonia evansiana, Bergenia, Carex ‘Evergold’, Cornus canadensis, Epimedium, ferns, Fuchsia magellanica, Heuchera ‘Key Lime Pie’, Heucherella, hostas, Lamium, Liriope, Lysimachia nummularia ‘Aurea’ (creeping Jenny), Pachysandra terminalis and Tiarella.
Perennials for a sunny position
Erigeron karvinskianus, Euphorbia, Festuca glauca, Helianthemum and sedums.
Pyracantha can be used to create a green wall simply by planting one against it and training the stems on wires.