Landscaping a Sloping Garden: Terraces and Retaining

Sussex gardens slope. Between the Downs and the Weald, a level plot is the exception, and the difference between a garden that works and one that is simply a hill with a lawn on it comes down to how the levels are handled.

Cut and fill

Terracing means cutting into the slope in one place and filling in another, ideally balancing the two so spoil does not have to leave site - a significant cost saving. Fill must be compacted in layers; skip that and the new terrace settles within a couple of seasons.

Retaining structures are engineering

• Above roughly a metre, retaining walls need engineered design and proper foundations
• Drainage behind the wall matters as much as the wall - water pressure is what pushes them over
• Options include reinforced concrete faced in stone, gabions, timber crib and dry stone for lower runs
• Never retain against a boundary fence, and check the position of neighbouring structures

Steps set the rhythm

Comfortable outdoor steps are shallower than indoor ones - generous treads and low risers - and consistent throughout the flight. Where a slope is long, breaking the ascent with landings gives places to pause and to plant, and makes the climb feel shorter than it is.

Drainage across the whole site

Water arrives at the bottom of a slope whether you plan for it or not. Interceptor drains at the top of terraces, permeable surfaces where possible, and a designed route to a soakaway or attenuation stop the lowest terrace becoming a pond every winter.

Planting a slope

Banks that are too steep to terrace can be planted to stabilise them - deep-rooting grasses, low shrubs and ground cover knit the surface together within two seasons. Mulch with a coarse grade so it does not wash off, and irrigate through establishment because slopes shed water fast.