The most evident planting style attempts to reconstruct a
plant community indigenous
to the location. Typically, they have relatively modest decorative value and in an urban
setting they do not cope as well as the more resistant weed species, however, the particular
importance of them is that these plants fit in most with the principle of biodiversity. When
such style is chosen in our climate, the almost completely bare winter condition needs to be
made friends with!
The vertical gardens that are constructed to
provide a more designed solution. In this case, indigenous or exotic, deciduous or evergreen
plants can be used. In such cases the plants are placed randomly into the system, then after
a while there will be some species that develop and some that die. The dominant conditions
change continuously; therefore the overall image of the wall will also change.
Modular systems provide solutions for facades depicting
images, logos and different patterns. These no longer try to copy nature; these are the
vertical version of the built garden in the traditional sense of the word. The different
gardening styles can be reproduced just as in a traditional garden.
The most intensive application is the vertical version of
, where the continuous winter-summer flower show can be ensured by swapping annual and
Climbers – without a support structure
(Hedera species): a very low demanding evergreen plant, although in hard frosts it can lose
its leaves. Little nutrient is required, it can be planted in sun, half-shade or shade, but
in a windy position its development is slow. There are many species with deep green or
variegated leaves and various shapes. The copious leaves can grow up to 15 cm in size,
covering each other. It uses its aerial roots to climb the wall, forming a 10-20 cm thick
(Campsis species): it can climb up to 8-10 meters height with its tendrils. It has large,
orange, yellow or red-cupped flowers from July to September in clusters. It has average
water requirements and likes rich soil. It favours sunny and warm position. It can develop a
considerable mass of foliage in both volume and weight, standing some 1-2 meters from the
wall. The stems may die back in winter.
(Parthenocissus species): It develops cohesive thin foliage on the façade. Many subspecies
exist, the shape and colour of the leaves as well as the growth orientation of the species
is the main difference. The autumnal colours of the leaves are very decorative. It can climb
up to 20 meters height. It is an undemanding plant, can cope with poor soil and tolerates
wide temperature variation. It can be planted to sunny, half-shady or shady positions,
although this shows some variations for the species. It uses suckers or tendrils to climb
Climbers – trained onto a support system
Climbing with tendrils: (clematis, wisteria, Dutchman’s pipe, Russian wine): Large species
and breed richness characterises this group. They can develop a significant weight of
foliage and some species have spectacular and attractive flowers. Deciduous plants.
Supported plants: (climbing roses, common beans): may require tying in
Winding or twisting: (honeysuckle, hops, morning glory Black-eyed Susan vine, silk vine): In
general the foliage is smaller in size than those climbing with tendrils. They have
characteristically decorative flowers, some are evergreen (facultative).
Cordons: (grapes): these require biding and for most species, intensive plant protection.
The grass provides a green surface in both winter and summer. It is popular and relatively
inexpensive, its operation is well understood, although it requires continuous mowing, which
on vertical surfaces is difficult to perform! Green walls tend to use grasses as mature
specimen plants or as a temporary decoration.
Typically a green area created based on the example of extensive green roofs, just
vertically. It requires little maintenance and minimal care. It tolerates drought well, and
only needs watering in extreme cases; therefore, in theory it could be an excellent choice
for low cost green walls. Unfortunately we are still waiting for a well-functioning
Annual and bi-annual flowers
They can provide intense decoration, however it requires continuous replacements, so when
choosing the carrier system it has to be one that tolerates frequent replacement well (e.g.
They have a more modest and shorter flower show than the annual plants; however, the range
is wide in leaf colour and appearance. Application options are primarily defined by the
characteristics of the façade (orientation, exposure). The rockery plants cope well with
full sun, while the shady perennials are best positioned in more protected sites. The
herbaceous plants have small rooting zones and live for several years. They can be used in a
cassette system as replacing them is easy. Perennials typically live for 2-3 years, perhaps
to 10 years, and offer the best solution amongst the annuals and shrubs.
There are smaller and larger plants among them, which, due to their larger rooting zone
needs, are less usable than the perennials. As the majority of the species and varieties
grown tolerate our winters (and generally this climate) rather well, and they are long
lasting, they are still a very valuable group of the plants for green facades. Unfortunately
only a few systems can accommodate them. The
system is suitable for accommodating the medium and weak growing species-varieties.
Orientation, sun exposure
These are key questions from a physiological aspect. One of them is the dominant wind
direction: the optimal plant orientation of the plants is obviously the side protected from
wind. Only a few plants are able to survive the in winter weather on walls where the plants
are exposed to the dominant wind direction or sweeping winds. The other equally important
factor is the length and strength of exposure to the sun: On surfaces where the average
annual direct sunshine is less than 3 hours daily, only explicitly shade tolerant plants can
be planted. Where the exposure is over 6 hours, plants that require a sunny position will do
the best (summer hot-spells may cause damage). In case of exposure between 3 and 6 hours,
plants recommended for half-shady positions are well suited; this is the most successful
level for constructing and operating a green façade.
The planting medium can be traditional soil or peat based substrate, organic fibrous medium,
foam based medium, mineral-based fibre or mineral based grainy medium. The traditional soil
and peat-based mixtures are not considered due to compaction issues. The mineral fibre
material also compacts due to the continuous contact with water, while the foam-based medium
is broken up over time by the roots, thus the life span of this latter one is short.
The mineral-based grainy mediums provide the best conditions for the roots. These porous
mineral materials have a stable structure and the humid environment between the grains
ensure a good root climate. In addition, they have good drainage characteristics, there is
no weed infestation and create conditions that is not desirable for the soil-dwelling pests.
The single disadvantage is that their pH value in general is slightly alkaline, which can be
corrected and maintained by setting the pH value of the nutrient medium. The acidic pH of
the feeding medium also prevents limescale build-up of the dripping holes.
The volume of the planting medium has to be able to accommodate as much root as is needed
for covering the water needs of the foliage. In the case of the pocket systems, the few mm
thick felt layer provides this medium. In comparison, the planting medium of the cassette
systems can be up to 20 times as much, with implicitly larger buffer effect and more
favourable physiological conditions.
Water and nutrients
The key factor for the survival of the plants is appropriate water supply. As vertical
gardens are typically more exposed to weather anomalies than their horizontal equivalents,
and the frequently mentioned balancing effect of the planting medium is significantly more
modest, the continuous, exact and even supply of water to the plants of the green façade is
vital. The water requirement of the plants strongly depends on the weather. In a long dry
and hot period, their water consumption could be multiple of the normal value, while in
permanent rainy-humid and cool weather it could decrease to a fraction of it. The climbing
systems with a soil connection are the most fortunate in this aspect, as the roots can reach
deep into the ground. The pocket system represents the other extreme; it has increased
sensitivity, only one missed irrigation cycle may cause problems. Water supply security can
be significantly increased by monitoring and automation.
It is important to note that in the case of green facades, in practice, we cannot really
count on the natural rainfall, which is especially true for walls on wind-protected
Nutrient supply on the green façade takes place in an entirely artificial manner, the
nutrient providing ability of the hydroculture planting medium is minimal. The composition
of the nutrient depends on several factors including the salt sensitivity of the plants, the
season as well as the given life stage of the plants. When providing the feeding medium,
great care must be taken as the feeding medium meets the rootlets directly and without
amelioration, thus even small feeding mistakes can cause severe root damage. The feeding
medium prescriptions should be prepared by professionals in all cases.
Living organisms threatening the plants of green facades include pests - caterpillars,
insects, mites etc., and different diseases caused by bacteria, virus or fungi. There is no
considerable difference compared with the protection of traditional ornamentals. The organic
planting mediums can harbour ground-dwelling organisms, while they are less likely to settle
in inorganic substrates as the airy structure does not provide appropriate conditions for
them. The health of the plants needs continuous monitoring and any threats have to be
recognised as early as possible. For protection against pests, it is worth involving a pest
control professional, which is also a legal requirement. In a given situation the damage
caused by humans may also be significant (including damage caused by pets).
This always depends on the given plant. Climbers have the longest life span, shrub type
plants can live for several years with appropriate maintenance: The older parts need to be
removed in order to provide room for the new ones. The annuals are best from spring to
autumn, the bi-annuals from autumn to spring. The life span of perennials is 3-10 years,
while the sedums continuously renew and change.
The most important maintenance task is monitoring and adjusting the water and nutrient
supply. The removal of plant parts that have died, dried up due to snow, freezing,
mechanical damage or sunburn as well as of blown flowers is included in the continuous
maintenance. Any changing and replacement of plants will probably be required sooner or
later on all walls; this should be taken into consideration when choosing a system, as the
suitability for this of the existing systems is not at all trivial. Pest control problems
and failure of the mechanical system may require occasional interventions.
For the more intensive systems (higher decorative value modular solution), continuous weekly
monitoring by a competent person is strongly recommended; this can take place on the site or
in part by remote control. In case of systems that are closer to nature and more extensive,
help from a professional is only required when specific problems arise; the maintenance
tasks can be performed by the staff on site. There can be several transitions between these
two extremes - the difference between them can be best described by the frequency of visits:
accordingly, this can be monthly, quarterly, every six months or annually dependent of the
parameters of the wall.
Use of plants
Adaptable to an extensive range of plants
The great strength of the system is that it does not use fixed module dimensions, but
variable ones adjusting to the size of the rooting zone required by the different plants.
For example, when planting shrubs, the module size can be increased by changing the
thickness and/or the overall size of the front of the module. The physically required
optimal volume for the roots - the physiologically most important part of the plant - can be
ensured in this way in all cases. This is a pre-condition for healthy and strong foliage as
well as for a rich flower display. The modules are designed to accommodate all types of
plants listed in the general section. This way, planting patterns, where the shrub patches
alternate with flowerbeds and grassy areas can be created – all these in one system and one
Instant green surface
The system can also accommodate completely mature plants, thus in green facades at premium
locations, where the full decorative value is expected on delivery, full coverage can be
provided. In cases of changes or replacement of plants, replacement can be with mature
plants, thus full coverage can be ensured without interruption. The distance between the
plants has to be scaled with consideration to the final foliage size, so they can provide
full coverage. The further developmental characteristics of the plants and the expected
formation of the foliage should also to be taken into account. In case of foliage growth, it
is possible to remove the plants from the module, like a chess board, thus the neighbouring
plants do not suppress one another, whilst still providing satisfactory coverage. This
solution permits the green façade to remain the same in several years’ time as per the
The formation of an optimised rooting zone
The parallelogram shaped cross-section and the narrow-tall frontal geometry of the module
was designed broadly keeping the growth tendencies of the roots in mind. The geotropic
nature of the plant roots suggests that it is physiologically more favourable for the roots
if the expansion options within the modules are vertical rather than horizontal. With this
cross-section design, it is possible to eliminate the “lower plant” effect described in the
“size coordination” section. The horticultural perlite medium provides perfect conditions
for the roots; in case of watering being accidentally missed, the vapour from the micropores
to the macropores can ensure living conditions for the roots for a long time. If the plants
are over watered, due to its excellent drainage, the roots will not be damaged and start
rotting. These two effects have been tested by drastic interventions (complete water
deprivation for two weeks in hot spells, as well as the addition of water triple the
quantity of what is optimal for months) on multiple counts. An additional benefit is it is
an excellent insulator in dry conditions, thus in the winter period, when there is no
irrigation, it protects the roots from the effects of cold air.
Quick and clean plant replacement
Fast changing of plants is provided by the design of the system, which permits the removal
of some modules without dismantling the whole wall - only two screws need to be unscrewed
and the module can be lifted out. The plant to be replaced can be simply lifted out and a
new plant can be added onsite there and then. All this can be completed in a matter of
minutes with the workspace also remaining clean. The characteristics of the system will be
unchanged even after unlimited replacements. Additionally, if the owner wishes to completely
renew the surface of the green wall, even after 10-20 years it will be possible to do so at
low cost, perhaps the replacement of the perlite will be required.
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