Written by Susan – Plant Lover, Adelaide
If you've ever tried to dig your Adelaide garden and hit what feels like modelling clay 10cm down, you're in good company. Much of metro Adelaide sits on heavy clay soils, particularly through the inner suburbs, the southern corridor, and parts of the northern plains. Clay soil gets a bad reputation — but with the right plants (and a few simple soil improvements), you can have a stunning garden.
⛏️ Understanding Adelaide Clay Soil
Clay soil isn't inherently bad for plants. It holds nutrients and moisture well — things sandy soil can't do. The challenges are poor drainage (roots can suffocate in waterlogged clay), compaction (roots struggle to penetrate), and cracking in dry summers (which can damage root systems).
The solution is two-pronged: choose plants that tolerate clay, and make simple soil improvements at planting time.
🛠️ Quick Clay Soil Improvements at Planting Time
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🟠 Add gypsum: Gypsum (calcium sulphate) breaks up clay particles and improves drainage without altering pH. Apply at planting and water in well.
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🟠 Raise the planting hole slightly: Plant so the root ball sits 3–5cm above surrounding soil level, then mound the backfill up to it. This ensures roots never sit in waterlogged soil.
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🟠 Add organic matter: Compost and aged manure improve soil structure over time. Mix through the top 30cm.
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🟠 Mulch heavily: Mulch protects clay soil from the sun-baking and cracking that makes it so damaging in Adelaide summers.
🌳 Trees That Thrive in Adelaide Clay
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🌲 Liquid Amber — Loves clay soils, particularly in the cooler months. Brilliant autumn colour.
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🌲 Ornamental Pear (Pyrus calleryana) — Performs well in clay with good drainage. White spring blossom and autumn colour.
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🌲 Eucalyptus varieties (small garden forms) — Most eucalypts are very clay-tolerant and thrive in SA conditions.
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🌲 Callistemon (Bottlebrush) — Native, clay-tolerant, and extremely water-wise once established.
🌿 Hedges & Shrubs for Clay Soil
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🟢 Photinia x fraseri (Red Robin) — One of the most clay-tolerant hedging plants available. We see it perform beautifully across heavy Adelaide soils.
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🟢 Viburnum tinus — Excellent clay tolerance. Reliable hedging shrub with winter flowers.
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🟢 Lilly Pilly — Handles clay well if planting hole drainage is improved.
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🟢 Westringia — Surprisingly clay-tolerant despite its coastal associations. Just ensure good drainage at planting.
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🟢 Grevillea (most varieties) — Native plants that evolved in variable Australian soils. Most handle clay with improved drainage.
🌱 Groundcovers for Clay
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🟢 Lomandra longifolia — Possibly the most clay-tolerant plant in our range. Virtually indestructible.
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🟢 Dianella (Flax Lily) — Handles wet clay periods and dry summers. Reliable year-round.
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🟢 Myoporum parvifolium — Native groundcover that spreads well even in clay with reasonable drainage.
❌ Plants to Avoid in Heavy Clay (Without Significant Soil Improvement)
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🔴 Lavender — Hates heavy wet clay. Will die quickly without well-drained sandy soil.
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🔴 Rosemary — Mediterranean origin means it needs free-draining conditions.
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🔴 Most succulents and cacti — Evolved for dry, free-draining soils. Will rot in clay.
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🔴 Roses (without soil preparation) — Can work in clay but need significant compost addition and raised beds for best results.
💚 Final Thoughts from Susan
"I hear 'my soil is terrible' all the time from Adelaide gardeners. But honestly? The right plants plus gypsum and mulch is a combination that works almost every time. Don't give up on your garden because of clay — choose the right plants and work with what you have. The moisture-holding capacity of clay is actually an asset in our dry Adelaide summers once you have plants that can handle it."
Browse our full collections and look for the 'Clay-Tolerant' tag in the plant details — or contact us for personalised advice on your specific garden.
