Sparkling Oasis
Take palms, tree ferns and other exotics,
and just add water. Landscaper Paul shows how it's done.
Paul Newman, Oasis Garden Services, 16 Alexandra Road, St. Albans,
Herts
Chamaerops No. 16, published online 23-08-2002
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Sparkling Oasis in 4 views.
Top left: General view of the garden, ready for turfing.
Top right: Construction-of the pools and cascade using 60 tonnes
of stone & rock.
Below left: Oasis in the frost; the finished garden has its ftrst
taste of winter.
Below right: The finished effect; cascade & top pool.
I am a landscape gardener and specialize in exotic,
'sub-tropical' and Oriental style gardens. One of my projects last
summer was the planning and construction of a large 'sub-tropical'
water garden.
A plan was drawn up, involving three pools, and
the main feature is a dramatic waterfall crashing into a sparkling,
cobble-filled pool. This then cascades over a series of weirs into
a larger, lower pool. To give you an idea of size, the approximate
dimensions are; header pool 1.5 X 1.5m (5ft X 5ft); middle pool
5 X 4.5m (16ft X 14ft); lower pool 8 X 7.5m (26ft X 24ft). As you
can imagine, this involved a vast amount of rockwork for the construction
of the waterfall, and to compliment the pools, some 60 tonnes m
fact! This was weathered York stone hand-picked from a quarry in
Lancashire. Some individual pieces weighed over a tonne.
The site was marked out and a large retaining wall
was constructed against which to position the header pool and to
form the basic structure for the waterfall. Rocks were then selected
with matching colour and strata layers so as to form natural-looking
rocky outcrops. Many pieces could not be lifted by hand and had
to be hoisted into position using a homemade A-frame, with block
and tackle. Even this proved insufficient for the largest rocks
and an excavator was brought in for the biggest. This was also used
to dig out the two pools to roughly the required dimensions, after
which they were completed by hand.
As the clients intention was to keep Koi carp, a
large and complicated biological filtration system was also built.
It consists of a series of chambers through which the water is drawn,
via the bottom pool, into a vortex. This spins the water, and any
sediment and waste is drawn to the bottom, and can then be flushed
through a bottom drain. The water is then forced through a chamber
containing a number of suspended brushes. This acts as a settlement
chamber and traps large particles. The water next weirs over two
further chambers containing filter matting, where bacteria breed
and colonize. It is these bacteria, which clean and detoxify the
water by breaking down the waste and ammonia levels produced by
the large fish. The final chamber is filled with 3/4" gravel
and filters fine particles. The whole system is powered by a one
horsepower ITT Marlon pump. To prevent algae and to keep the water
clear, two ultra-violet light units were installed. The UV rays
produced by the lights kill off the bacteria as the water passes
around the protective tubes. The entire system is below ground level,
and wooden hatches are fitted to enable access to the chambers and
pump for maintenance. These are in turn hidden by wooden decking,
which forms a seating area.
Once the pools were dug out and levelled, they were
lined with 2" of sand and a Geotex underlay which cushions
the thick Butyl liner against the very heavy rocks which were later
positioned in the pools and on the shelf around the perimeter. As
well as the 60 tonnes of York stone that surround the pools and
waterfall area, four tonnes of Scottish beach cobbles were used
to create a wide, sloping beach, leading into the lower pool. These
have a wonderful colour when wet and will be visible under the water,
kept clear with the filtration system. A bog garden was added to
one side of the lower pool, and planted up with large, lush foliage
plants including Ligularias, Lysichiton americanum, Peltiphyllum,
etc., not forgetting the obligatory and monstrous Gunnera manicata
which will overhang the water's edge, casting mysterious shadows
in the dappled light.
After much backache from lifting heavy rocks and
some final adjustments to the waterfall - the focal point - we could
begin the planting. All the plants were chosen for their strong,
architectural shapes and large, lush foliage to give a really exotic
effect. Palms include 6 Trachycarpus fortunei - two at lOft and
the rest about 5ft, 4 bushy Chamaerops humilis and a superb Butia
capitata which was already beginning to form a thick, heavy trunk.
Three of the Trachy's are planted in a group and look stunning as
their crowns are at different heights. The other tall one stands
on its own and looks wonderful together with its reflection in the
pond's surface. The two remaining Trachys are planted either side
of a winding pathway that runs around the back of the bog garden
to the sitting area on the decking covering the filter chambers.
As the path snakes its way around, a jungley effect
has been created by planting a grove of Phyllostachys aurea. The
clumps of this bamboo are up to l5ft in height, and possess some
wonderfully knobbly canes. Arundo donax (Spanish Reed) together
with its variegated form add to the general effect. The sitting
area referred to above has been made into a 'secret' place by the
use of Phyllostachys nigra, the Black Bamboo, whose impressive,
shiny, ebony canes (or culms) help to create the mysterious, jungley
effect. On the left hand side of the waterfall Fatsia japonica and
the large evergreen ferns Blechnum chilense, Polystichum setiferum,
and the bright green Asplenium scolopendrium are planted in gaps
and crevices between the rocks. The centrepiece here is a beautiful
Dicksonia antarctica tree fern, with its graceful, spreading fronds
arching out over the pool. The spray and mist from the waterfall
keep its foliage and trunk moist, and provide the humidity that
this plant loves.
The right hand side of the waterfall is planted
with Sasa palmata. This is one of the best tropical-looking bamboos,
as it possesses large, palm-like leaves up to 16" long and
4" wide. In front of the group of three Trachys a huge, jagged,
wedge-shaped piece of rock has been half buried and looks as though
it has exploded out of the ground. Here a group planting of Phormium
tenax purpureum and the dwarf variegated bamboo Pleioblastus variegata.
The Butia capitata is planted by the cascade section leading to
the lower pool, along with Chamaerops humilis the two different
leaf shapes and colours making a wonderful contrast.
Continuing further around the edge of the pool the
path splits into two directions, one way leading back towards the
house around an island bed containing more Chamaerops humilis and
Cordyline australis. In the other direction, the path continues
towards the lower beach area where the cobbles extend out of the
water. Here a raised area has been created and planted with Agave
americana and Yucca recurva. The Agaves will need protection only
in the coldest weather and I am confident that they will do well
as they are planted in extremely well drained sandy soil and receive
full sun all day.
To the left of this area, a large bed has been created
and planted with various Phormiums together with Eucalyptus niphophila,
the Alpine Snow Gum. This attractive tree is one of the best Eucalypts
for bark pattern and colour. As the tree grows, the bark stretches
and cracks or splits to reveal the new inner bark, a marbled pattern
combining grey, green and cream. The young stems and branches are
bright red and glossy and form a beautiful contrast with the glaucous
leaves and the colourful bark pattern.
Also here is Melianthus major. This large South
African plant forms large, serrated, deeply cut leaves, and is a
must for foliage lovers. This area will also be used to plant out
the more tender exotics including the beautiful Cannas with their
lush, banana-like foliage and exotic flower spikes. The purple forms
are very attractive as are the wine-red leaves of Ricinus communis,
the true Castor Oil plant. The variety 'Gibsonii' is the best and
is an annual, easily grown from seed. The largest and perhaps the
most stunning tender exotic has to be the Abyssinian Banana, Musa
ensete. This huge plant can reach 18ft (5.5m) in height with leaves
up to 12ft in length in a surprisingly short time and would surely
be the pride of anyone's garden. Sadly it is not frost hardy and
must be protected in winter. This is best done by lifting it in
autumn and overwatering it in greenhouse or conservatory. The Japanese
banana, Musa basjoo, may be grown all year round in sheltered gardens.
Even when cut to the ground by frost, it will shoot again the following
season and is very vigorous.
All the plants mentioned are surprisingly easy to
look after and require the minimum of maintenance and care and will
reward you year after year with superb displays of exotic foliage
and colours.
After planting, the next job was the construction
of the pathways and lawn area. A winding pathway leads from the
patio and runs around the perimeter of the water garden, and thence
to the lower lawn. This was edged with 'log roll' edging and haunched
with a render mix to keep it firm and level. A layer of compacted
hoggin was added to act as a sub-base. This was topped with 3"
of grey/green stone chippings and makes a good contrast to the weathered
York stone rocks. Sections of log were laid along the path to form
a stepping stone effect. The two main lawn areas were rotavated,
dug over and raked to a fine tilth to enable the fine quality turf
to be laid. A smaller lawn area behind the grove of Bamboo and Phormiums
creates a mysterious 'hide-out' and also has the best view-point
in the garden as the waterfall can be seen from a distance, sparkling
as it catches the sunlight between the arching canes of Phyllostachys
nigra.
Specimen trees are to be planted in the lawn areas
and include Pinus pinea, the Italian Stone Pine, Paulownia tomentosa
which, if pollarded every year will produce huge, soft, velvety,
yellow leaves, and Cercidiphyllum japonicum. These, together with
various Acers will be planted for their brilliant displays of autumn
foliage, to complete the scene.
Though of course it will take a while to achieve
maturity, even the early effect of the garden is one of a lush,
tropical oasis. I hope this article will serve to inspire all palm
fanatics, and will give an idea of the wonderful effect that the
combination of palms, other 'exotic' plants, together with water
can achieve, irrespective of the size of the garden.

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