Our Robertson Garden Journey
Stage 1- Removal of a drab Moonscape
In 2014, the east side of our house was a moonscape of white pebbles and a railway sleeper walk. Not one plant. In addition, the pebbles were under laid with heavy duty silage plastic. This presented multiple problems: Firstly, moisture tended to pool on the surface during heavy downpours because there had not been proper earthworks to engineer a fall or incline that would drain stormwater, and the rainfall could not infiltrate the silage membrane. Secondly, moisture trapped below the membrane and could not evaporate, leading to a more or less permanently spongy surface.
This all had to go.
The House as it was in 2014:
Figure 1 - Northeast corner in 2014
We were determined to fix the lack of plants on the east side of our new home – and to remove the very basic landscape of fine white stones and sleepers
Figure 2 - East side of house looking North 2014
Figure 3- East side of house: Preparations for the earthworks - A desert of white pebbles; most of the sleepers have been removed, see the white silage plastic underneath. July 2016
The Design Plan:
- Remove the railway sleepers, white stones, and silage membrane underneath.
- Earthworks to create a gradient to drain stormwater towards the rear of the house.
- Installation of a white Stratco awning in the centre section of the house with no eve,
(another builders shortcut to compensate for the internal cupboards in the corridor)
- Removal of side fence and gate.
- Concrete slab to be installed underneath awning.
- The rest of the east side of the house to be laid with drainage cells with new darker mixed colour blue metal inside the drainage cells. During a future Robertson ‘classic deluge’ (during an east coast low pressure system), the drainage cells can allow several days constant rainfall of hundreds of millimetres to infiltrate the soil. When soil reaches field capacity (saturation), the water will flow alongside the raised sleeper garden bed and not the house wall, and into the backyard away from the house.
- Construction of a 28.5m raised bed of stained treated pine sleepers along the fence line to form a mixed shrubbery and screen that allows some light through while creating privacy.
- Drainage cells to wrap around the northeast corner in front of the water tank to form a path to the deck.
Figure 4 Nov. 2016 - Earthworks & stormwater completed, retaining posts for garden bed in place
Stage 2 – Earthworks & Stormwater Drainage
Once the tedious white stones and sleepers moonscape was removed, then the plastic membrane was pulled up – exposing the soil. The soil was graded with an excavator by the concrete contractor who placed a fall of approximately 100-150mm from front of the house to the rear all along the east side. This was to stop water ponding around the house as it did prior to these works being completed.
The Step on the left of the photo above was excavated for the 28.5m raised bed to be planted out with mixed ornamental shrubs. We decided against a solid high hedge on the grounds that too much shade would result in the early morning. Excavated soil was stored in backyard for the backfill of the garden bed.
Figure 5 - Awning and concrete slab completed, drainage cells being installed, raised bed sleepers installed
Stage 3 – Eastern Raised bed, Awing & drainage cells
The Stratco awning was installed first. The timber sleepers were laid down inside the galvanised retaining posts, then the concrete slab was poured and screed before the drainage cells could be laid butting up against the sleepers. The idea is that water entering from the front yard will flow northwards along the raised bed away from the side of the house. Initially the stormwater will drain into the pits, with any overflow during extreme rainfall events flowing out into the backyard and across it into the adjacent lane on the west side of the property.
Figure 6 Drainage cells laid on a base course of 100mm of compacted blue metal.
Figure 7 - The drainage cells form a path to the deck
Figure 8 - completed drainage cells installation and garden bed retaining sleepers – raised garden bed is being backfilled with stockpiled soil from excavation for concrete slab.
*Note the drainage cells are awaiting the final stage of filling with blue metal.
Figure 9 - The drainage cells laid to form an eye-catching pattern, level perfect.
Figure 10 - Drainage cells wrap around the NE corner
The Plant List
The Mixed Shrubbery:
- Deutzia ‘Magician’
- Kolkwitzia amabilis Beauty Bush
- Camellia sasanqua spp. ‘Pure Silk’; ‘Something Special’; ‘Cherilyn’; ‘Jennifer Susan’; ‘Hiriyu’;
- Viburnum plicatum ‘Mariesii’ Japanese Snowball Tree
- Viburnum Juddi
- Viburnum macrocephalum Chinese Snowball Tree
- Viburnum opulus Snowball Tree
- Weigela florida
- Osmanthus delavayi
- Cytisus x dallimorei ‘Volcano’
The Perennials
- Salvia guaranitica ‘Black and Bloom’
- Salvia ‘Hot lips’
- Salvia ‘Black Knight’
- Phlox sp.
- Azalea spp.
- Acanthus spinosus
- Clematis spp.
- Astilbe chinensis ‘Purpurkerze’
- Digitalis spp.
- Iris spp.
- Penstemon spp.
Figure 11 – Spring 2017: East Bed landscaping completed, soon after planting. Drainage cells filled with blue metal mix
Figure 12 – Early Spring 2019; 2 years after planting looking north along the east side of the house
Figure 13 - Spring 2019 Dutch Irises in the foreground
Figure 14 - November 2019 – Facing south
Figure 15 - November 2019 – facing north
Figure 16 - November 2019 – Facing south
Figure 17 - November 2019
Figure 18 - November 2019