Garden Up The Wall
We are all familiar with using plants to cover walls and fences but these are normally
planted in soil at the base of the structure and either self-cling or are encouraged
to climb with the use of supports. The latest trend is for plants to be grown on
the wall itself allowing the designer to use their skills to create wonderful patterns
of colour and texture on the vertical plane.
The grand master of vertical planting has to be Patrick Blanc whose work adorns
the facades of hotels, office blocks and museums around the world. One of the best
locations to view his work is Paris where several gardens have been installed including
part of the façade of the Musée du Quai Branly which is one of the largest and easiest
to view, being just around the corner from the Eiffel Tower.
Inspiration for his work came from travels to parts of the world such as Malaysia
and Thailand. At first sight it is easy to think the planting is tropical but in
fact the majority of plants are from temperate regions and are commonly found in
any garden for example Heuchera. The reason for the tropical image is possibly due
to the choice of plants that grow on rocks or soil-less slopes in their natural
environment and the planting of species on slightly-tilted, near-vertical lines
imitating the lines of rock strata.
The structure behind the planting consists of a metal framework covered with a waterproof
layer of pvc. Onto this is stapled a double-layer rot-proof felt that has excellent
capillary action into which a cut is made in the top layer, forming a pocket into
which the plants are pushed. The irrigation water uses run-off from the roof and
is enriched with high level nutrients and runs into a trough at the bottom of the
wall and is then pumped back to the top. As the roots do not need to search for
food they remain on the surface so causing no damage to the buildings. In essence
it is hydroponics on a large scale.
The next stage of this gardening revolution is to make it viable for regular gardeners.
With gardens of new-build properties getting ever smaller it is becoming more critical
that every inch of space is considered for planting. At Chelsea 2008 three show
gardens included vertical planting and generated much interest from the general
public. Mark Gregory, designer of the gold-medal winning Children's Society Garden
took his inspiration from Patrick Blanc but wanted to create vertical planting in
a way that could be replicated by visitors to Chelsea.
Mark's method of construction used compartments resembling wall-mounted bookcases
with both horizontal and vertical dividers. The structure was built from western
red cedar which is very sappy and rot-resistant but plastic or metal could also
be used. Whatever type of frame is used the depth needs to be enough to hold a good
quantity of very free-draining material with built in irrigation such as a drip
line. Small plant plugs should be used and secured using galvanised mesh, starting
from the bottom. Obviously all the 'shelves' need holes so that water can drain
down but the final key to success is to use drought-tolerant species such as Sedum
and Sempervivum at the top and moisture-loving Euphorbia and Asplenium at the base.
The 'wall' should be planted in its final position as it will be impossible to move
once everything is in place.
Phillippa Probert, designer of the Green Living Garden also said "Patrick Blanc
and his 'living walls' have been an influence on this garden, but I’m trying to
create vertical planting in a way that can be copied and replicated by people coming
to the flower show."
Unfortunately it is unclear exactly how sustainable planting in soil units might
be for the domestic gardener as so far in the UK the majority of planting has taken
place on large commercial installations. A modular system suitable for commercial
or domestic applications has been developed and used in Canada with modules constructed
from 100% recyclable black high density polyethylene but as yet it appears no such
system exists in the UK. It can only be hoped that if designers show enough interest
in this style of planting there may be a manufacturer out there willing to invest
in the technology.
Only time will tell if vertical gardening is a truly practical idea. At the Musée
du Quai Branly there are now substantial areas bare of plants, mainly lower down
the wall and probably as a result of constant touching from intrigued passers-by
and it appears that not all the water is recycled as much does drip down onto the
pavement rather than returning to the trough. However, these are small quibbles
of a truly ingenious idea that has so many benefits for the urban environment.
Today, the environmental agenda is a hot topic and both small- and large-scale vertical
planting could be a useful tool in the battle against climate change. The addition
of a living wall reduces the need for heating and cooling so lowering carbon emissions
and with less reflected heat the heat island effect can also be reduced. Plants
help to absorb rainwater so can be used as another weapon in the arsenal to combat
flooding in built-up areas and they help filter pollution and baffle sound. In fact
research by the Centre for Sustainable Development at the University of Cambridge
has found that a layer of vegetation can reduce heat loss from buildings, cutting
the wind chill factor by 75% and heating demand by 25%. If this wasn't enough, vertical
planting done well is a thing of beauty adding a whole new meaning to 'urban jungle'.
Update: November 2008
Patrick Blanc's first UK commission has just been completed at the new Leamouth
Peninsula development in London's Docklands. At 820sq metres, it is Britain's largest
green wall containing 30,000 plants of 160 different cultivars. The wall was installed
by BioTecture Ltd.
If you have any questions or comments about this article
let us know.
Read a review of Patrick Blanc's book The Vertical Garden:
From Nature To The City
© Sharon Brown
19th November 2008