VERTICAL GARDENS INSPIRED BY NATURE
Nature can guide any gardener, horizontal or vertical. Choosing the right plant for the right place means matching growing conditions in the garden with those in nature. Looking at vertical gardens from this perspective, nature is a reference both in plant selection, design and optimizing the growing technique.
THE VERTICAL HABITAT
The most common vertical growing locations in nature are tree trunks and cliff faces, places characterized by little soil, good drainage and a solid surface for roots to attach to. While today there are many techniques available for creating vertical gardens, the felt technique most accurately replicates these growing conditions. Like a moist cliff face, a felt attached to a rigid backing board constitutes a well-drained, solid and practically unlimited growing surface.
These conditions allow roots continuous growth, unlike a pot that restricts growth of the plant, hindering it to reach its’ full potential. Large growing plants can trail freely along the surface while anchor roots attach the plant securely as it grows larger and heavier over the years.
With the vertical habitat in mind, let’s look at some examples of interesting and useful plants for the indoor vertical garden. The indoor environment normally has low light levels and a temperature around 20 C, which in nature would correspond to a shadowed tropical environment, e.g. below a forest canopy.
Aroids (Araceae) is a plant family with many epiphytic (growing on other plants) and semi-epiphytic species having spectacular foliage, well suited as eye catching accent plants. Common aroid genera are Anthurium, Philodendron, Alocasia, Aglaonema, Monstera, Epipremnum, Scindapsus and Syngonium.
Philodendron giganteum is as the name implies a large growing aroid. It is a terrestrial or rock growing plant native to parts of the Caribbean and northern South America. An easy plant to grow on a vertical garden and after a couple of years it folds out impressive leaves.
Philodendron gloriosum is another fine accent plant, whose main feature is the dark, velvety leaves, with white veins accentuating the shape.
Hedychium is a Southeast Asian genus with several species suitable for indoor conditions. Branches can reach out 1-2m from the wall and bear large flowers each year.
Begonia is a large genus and additionally very popular with breeders, producing seemingly endless cultivars with any imaginable leaf color, size and growth habit. Begonia listada is a quite small plant native to Brazil. Frequently flowering and with dark velvety leaves with a light pale line in the middle. Combined with other smaller plants it can make an eye catching contrast.
Leaving aside overall aesthetic objectives there are many characteristics of a plant that should be considered in the planting layout, as well as shifting growing conditions within the wall area.
- •Light level – Normally there is more light in the top and middle of surface (light intensity is inversely proportional to the square of the distance from the light source).
- •Moisture level - As the water gravitates down there is more moisture in the bottom of the surface.
- •Maintenance - A plant’s characteristics will influence future maintenance demands. Plants should be located and combined in a manner so the plants natural growth habit can unfold without creating unnecessary maintenance demands.
- •Accent plant or group plant – some plants are great to plant in groups to create a green cover, while others have interesting features that becomes less prominent while planted in groups.
- •Growth habit – The plant’s growth habit - cascading, pending, climbing, creeping etc. - shapes the garden’s dynamics.
- •Size – A large plant may create deep shadow below itself where other plants hardly thrive.
- •Foliage density – Less dense foliage lets light pass through, allowing combinations with other plants.
- •Leaf color – Besides the shades of green, contrasting colors can effectively bring out and intensify the greenery.
- •Leaf shape and texture – Linear or round, shiny, hairy, velvety, wrinkly, waxy…
- •Flowering - Plants suited for indoors tend to have modest flowering, but there are some exceptions that can be a focal point.
- •Smell – Tropical plants rarely smells anything like Mediterranean aromatics, but there are some exceptions that have interesting smell when touched or a leaf is broken.
Indoor vertical gardens tend to be planted mainly with the same few plants and it is a loss of opportunity not to take advantage of the wide range of plants that actually thrive in these locations. Using a large number of species is no goal in itself, but there are benefits of diversity. Pest insects usually invade one or a few species at a time, so a divers selection is more resistant. And although it may be far-fetched to compare vertical gardens to a nature experience, it is also notable that research show health benefits, psychological and physiological, of experiencing nature and indicate that people’s aesthetic appreciation increases with species richness.
I believe the main benefit of using living plants in an urban context is the connection to nature they provide. Vertical gardens allow dense plantings even in confined spaces and may with careful design be a vibrant slice of nature in the built environment.
Michael Hellgren is a Swedish landscape architect and founder of Vertical Garden Design, represented in the UAE by Gover Horticulture.
1 Poorter, H., et al., 2012. Pot size matters: a meta-analysis of the effects of rooting volume on plant growth, Functional Plant Biology 39, 839-850.
2 Sandifer, P.A., et al., 2015. Exploring connections among nature, biodiversity, ecosystem services, and human health and well-being: Opportunities to enhance health and biodiversity conservation, Ecosystem Services 12, 1–15.
3 Lindemann-Matthies, P., et al., 2010. The influence of plant diversity on people’s perception and aesthetic appreciation of grassland vegetation, Biological Conservation 143, 195-202.
The article can also be found here.