Gardening on clay soil in western Sydney
Heavy clay holds water in winter and sets like brick in summer. Why it's hard on gardens across western Sydney, and what actually helps plants and lawns grow.
A lot of western Sydney sits on heavy clay. If you've ever dug a hole there, you'll know. In winter it's sticky and wet. In summer it sets hard and cracks. It's tough on lawns and plants, but you can garden on it well once you know how it behaves.
Clay holds water. Its tiny particles pack close together, so water drains through slowly. After rain, roots can sit in wet soil for days and rot. That's why lawns on clay often squelch in winter and why some plants die for no clear reason.
Then it dries out. In a hot summer, clay shrinks, cracks and goes rock hard. Roots can't push through it, and water runs off the top instead of soaking in.
Don't dig it wet. Working clay when it's wet squashes it and makes it harder, like brick. Wait until it's moist but crumbly. If it's rock hard, water it the day before.
Don't dig a hole and fill it with good soil. It seems like a fix. But the hole acts like a bathtub. Water drains into the loose soil and can't get out through the clay around it, so the roots drown. Improve the whole bed instead, or build it up.
Add compost, again and again. Organic matter, like compost and old manure, helps clay crumble and drain. It won't change overnight. Add it each time you plant, and keep a layer of mulch on top. Over time the soil gets easier to work.
Raise the beds. Where drainage is poor, build beds or mounds above the clay. Roots get loose soil to grow in, and extra water can drain away.
Pick plants that cope. Plants that handle wet feet in winter and dry spells in summer do best. Many plants native to the area grew up on this clay. Ask for plants suited to clay soil, not just what looks good in the pot.
Water slowly. Clay soaks water up slowly. A fast spray runs off. Water deeply and slowly, less often, so it soaks down to the roots.
Keep the ground under the lawn right. Turf laid straight onto hard clay struggles to root. It needs a layer of good soil under it and ground shaped so water runs off. Our guide on why lawns keep dying goes through it.
If a corner of your yard stays wet all winter, see our drainage page. For new beds and better soil, see planting and soil. Soil changes from street to street, so we check yours before we plant a thing.