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How to improve Perth's sandy soil (so water finally soaks in)

Perth gardens sit on some of the oldest, sandiest soil on earth — it repels water when dry, holds no nutrients, and eats fertiliser for breakfast. The fix is real and permanent, but it's a sequence, not a product: wetter, clay, compost, mulch.

Step 1: break the water repellency

Dry Perth sand grows a waxy coating that makes water bead and run off — you can water daily and the root zone stays dry. A soil wetting agent strips that coating for a season. It's the cheapest, fastest improvement on this list: apply in spring and again in early summer.

Step 2: add clay to hold water

Wetter lets water in; clay makes it stay. Kaolin or bentonite clay amendments, dug into the top 150–200 mm, permanently change how sand holds moisture and nutrients — it's the difference between watering a sieve and watering a sponge. One thorough application per bed, once, is a decade's fix.

Step 3: feed the soil with compost

Compost and soil improver bring the biology — worms, microbes and organic matter that turn dead sand into living soil. Dig it through new beds generously and top up existing beds each year; in Perth sand it breaks down fast, so little-and-often wins.

Step 4: mulch to protect the work

Everything above evaporates away if the bed bakes bare. A 75 mm mulch layer keeps the moisture and biology you just built — lupin mulch doubles as a slow compost feed while it protects.