Paul Roper-Gee of Canopy Landscape Architects plants some tips on how to make the most of space in a hillside garden with considered retaining, platforms and planting.
Christchurch’s volcanic past has created our hill suburbs with varied topography and aspect, making for unique and individual gardens. The dramatic views to the Southern Alps, estuary and seascape together with nearer views of the Port Hills are a key feature of Christchurch hillside gardens. Creating successful gardens on these slopes comes with design opportunities and challenges.
One trade-off is the strong winds. To resolve this, consider where your key views are and make them open, while creating sheltered and intimate spaces in other parts of your garden. Use plants for wind shelter, because solid walls do strange things with wind funnels.
One approach to gardens on a slope is to work with the hill. Think meandering paths and steps across the slope. This approach works well with creative planting to provide an immersive garden experience.
Another approach is to create flat space through terracing or decking. For terracing, try planning for several low walls with level terraces between instead of one big retaining wall. This way you can create individual garden ‘rooms’. A comfy outdoor entertainment area in the right position provides a great place to sit and survey the rest of your garden. Decking can create flat space that floats above a slope, and a multi-level deck can add valuable outdoor living space. The contrast between natural plantings and decking is always striking.
Most Christchurch hillsides are formed from loess soils over volcanic bedrock. The loess can be boggy in winter, and then bake rock hard in summer. Plan drainage carefully and add organic material into the soil to improve the growing conditions for planting. Bedrock can be just below the surface or metres deep, and can vary considerably across one property. The depth of bedrock can determine the most suitable construction methods for the site – for example whether you use timber piles or concrete foundations for retaining walls.
Be conscious of council planning requirements – there are limits on the amount of earthworks you can do before you’ll need a resource consent. When building a new house, try to factor garden earthworks into the consent application for the house.