The right plants can transform a retaining wall from a purely functional structure into a living garden feature. Plants soften hard edges, add colour and texture, prevent erosion on the soil above and below the wall, and even contribute to the wall’s structural performance by stabilising the retained soil with their root systems. This guide covers the best plant choices for retaining walls in Adelaide and South Australia, including ground covers, trailing plants, climbers, and species to avoid.
Ground Covers for the Top of Retaining Walls
Plants along the top edge of a retaining wall serve both aesthetic and functional purposes. They soften the visual transition between the wall top and the garden above, and their roots help stabilise the soil immediately behind the wall. For Adelaide conditions, native ground covers are ideal because they are adapted to the local climate and require minimal watering once established. Myoporum parvifolium (Creeping Boobialla) is a standout choice, forming a dense, low mat of fine foliage with white star-shaped flowers that trails beautifully over wall edges. Grevillea ‘Royal Mantle’ and Grevillea ‘Bronze Rambler’ provide a cascading effect with burgundy-bronze foliage and red flowers that attract honeyeaters. Carpobrotus rossii (Native Pigface) is extremely drought-tolerant and thrives in Adelaide’s hot summers, making it perfect for exposed north-facing walls. For a non-native option, trailing rosemary (Rosmarinus officinalis ‘Prostratus’) drapes elegantly over wall faces, is highly drought-tolerant, and provides fragrant foliage for cooking. Avoid aggressive ground covers like Kikuyu grass or Tradescantia, which can invade the wall’s drainage system and compromise its structural integrity.
Trailing and Cascading Plants for Wall Faces
Plants that cascade down the face of a retaining wall create a dramatic softening effect, particularly on tall or imposing walls. For concrete sleeper walls and block walls, install planting pockets or place plants in the soil immediately above the wall to allow them to trail over the edge. Star Jasmine (Trachelospermum jasminoides) is one of Adelaide’s most versatile wall plants, producing fragrant white flowers in spring and maintaining dense evergreen foliage year-round. It can trail down or climb up, depending on where it is planted. Hardenbergia violacea (Native Sarsaparilla or Happy Wanderer) produces masses of purple pea flowers in late winter and early spring, bringing colour when much of the garden is dormant. For a silver-foliaged option, Dichondra argentea ‘Silver Falls’ creates a stunning waterfall effect of silvery leaves cascading up to 1.5 metres down a wall face. These trailing plants are particularly effective on gabion walls and sandstone retaining walls, where the natural material texture combines with living foliage for a truly organic appearance.
Climbers for Bare Wall Faces
Climbing plants grown up the face of a retaining wall add greenery and can disguise less attractive wall surfaces. Self-clinging climbers like Ficus pumila (Creeping Fig) adhere directly to smooth surfaces, eventually covering the entire wall face with dense, small-leaved foliage. While Creeping Fig is excellent for creating a living wall effect, be aware it is vigorous and requires periodic trimming to prevent it from reaching roof lines or smothering adjacent structures. For a more controlled climber, install a wire trellis on the wall face and grow twining plants such as Pandorea jasminoides (Bower of Beauty), which produces pink trumpet flowers and has moderate vigour. Native Clematis microphylla offers delicate white flowers and fine foliage without the aggressive growth of some introduced climbers. For walls below garden beds, plant climbers in the lower garden area and train them up the wall face. Ensure that any climbing plant’s root system is positioned at least 300mm from the wall base to avoid interfering with the drainage system behind the wall.
Plants to Avoid Near Retaining Walls
Some plants cause significant damage to retaining walls and should be kept well clear. Trees with invasive root systems are the primary concern. In Adelaide, River Red Gums (Eucalyptus camaldulensis), Willows (Salix species), Fig trees (Ficus species, excluding the small Ficus pumila), and Pepper Trees (Schinus molle) all have aggressive root systems that can displace wall footings, block drainage pipes, and push walls out of alignment. Keep these species at least 3 to 5 metres from any retaining wall. Bamboo, while not a tree, has a rhizome root system that can exert enormous pressure on retaining walls. Running bamboo species should be kept at least 5 metres from walls, and clumping varieties at least 2 metres. Agapanthus, while commonly planted near walls, has a dense root mass that can block weep holes and drainage, and its clumping growth can eventually dislodge capping stones. If you plant Agapanthus near your wall, position it at least 500mm from the wall face and keep it trimmed. Large shrubs planted directly behind a wall can increase the surcharge load on the retained soil, particularly when wet. Discuss planting plans with your builder to ensure new plantings do not compromise the wall’s structural design.
Planting Tips for Adelaide Conditions
Adelaide’s Mediterranean climate of hot dry summers and cool wet winters influences plant selection and establishment timing. Autumn (March to May) is the best planting season for retaining wall plants in Adelaide, giving roots time to establish during the cooler months before facing their first summer. Mulch generously (75mm depth) around plants near walls to conserve moisture and suppress weeds, but keep mulch clear of the wall face to prevent moisture damage. Install drip irrigation for plants above and at the base of retaining walls, as the free-draining backfill behind the wall means soil near the wall dries out faster than surrounding garden areas. For walls in full sun (north and west-facing in Adelaide), choose the most drought-tolerant species, as reflected heat from the wall face intensifies summer conditions. Walls in shade (south-facing) support a wider range of plants but may develop moss and algae on the wall surface, which is generally cosmetic rather than structural. For comprehensive ideas on combining retaining walls with garden design, see the garden retaining wall guide.
Designing a planted retaining wall for your Adelaide garden? Connect with retaining wall builders who understand landscaping through our free matching service. Many of our builders work with landscape designers to deliver walls that are both structurally sound and beautifully planted.