Global Gardening

A garden that copes with dry weather starts below the surface. Plant choice matters, but the soil decides how much of your water the roots can actually use. Get both right and you will water less often.

Australia covers many climates, so there is no single formula. Some of the figures below come from Western Australia, where the Water Corporation publishes detailed advice. Check what applies in your own state and council area before you copy any numbers.

Start with the soil you have

Pick up a handful and look at it. Sandy soil feels loose and gritty. Clay soil feels sticky and holds its shape when squeezed.

Each type has its own weak spot. According to the Water Corporation guide to improving your soil, sandy soil has a low capacity to hold water and nutrients. It also commonly becomes non wettable, which means water runs off or pools instead of soaking in.

Clay holds plenty of water but can drain poorly. The Water Corporation’s five steps to a waterwise garden suggest adding organic matter and gypsum to the top layer of clay heavy soil before planting. Organic matter helps both soil types, just in different ways.

Improve the soil before you plant

Timing helps. The Water Corporation says to improve soil before planting a new garden, preferably in late autumn. That gives the bed time to settle before the warmer months arrive.

For a mass planting, the advice is to mix organic matter thoroughly through the top 30 centimetres of soil. For a single plant, dig a hole twice the depth and width of the pot. Discard a third of the existing soil and mix organic matter into the rest.

The same page recommends the single plant method for established beds. You do not need to dig the whole bed over to add one shrub. Work on each planting hole instead.

Wetting agents and pH

A wetting agent helps water enter soil that repels it. The Water Corporation recommends applying one at planting and again at the start of winter, in early spring and in early summer. Water it in so it activates.

It also notes that a fairly neutral pH of 6.0 to 7.0 suits most grasses and plants in Western Australia. Soils in other states can sit well outside that range. A simple test kit from a garden centre will show where yours sits before you add anything.

Choose plants that suit your climate

Local plants are a sensible place to begin. The Water Corporation says Western Australia has hundreds of native and exotic species that suit its climate. It adds that waterwise plants need less water and less maintenance.

That principle carries across the country. A plant from your own region already copes with your rainfall, your soil and your summers. Your local nursery or native plant society can name the species that do well nearby.

Think about the whole plant, not just its water needs. Check its mature height and spread before you buy, and leave room for it. These landscape design principles for smaller gardens explain how to fit plants into a tight space. A small tube stock plant can grow into a large shrub within a few seasons.

Group plants by water needs

The Water Corporation suggests grouping plants with similar water needs. This is often called hydrozoning. Thirsty plants sit together near the house or the tap. Tougher plants sit further out.

The payoff is simple. You can water each zone to match what it needs, rather than drowning one plant to keep another alive. Good grouping also helps in a small yard, where every square metre has to work.

Mulch properly

Mulch is one of the cheapest upgrades you can make. The Water Corporation recommends a layer of 5 to 10 centimetres across the soil surface. It says mulch can save up to 20 per cent of the water used in the garden.

Keep mulch clear of plant stems so they do not stay damp against the bark. Use chunky, coarse mulch around shrubs and trees. Use a composting mulch such as straw or lucerne in vegetable gardens and around delicate plants.

The Water Corporation also advises buying from an accredited supplier whose mulch is certified free of weeds, pests and diseases. That protects your beds from unwelcome extras. Check the layer now and then and top it up when it thins.

Water to need, not to habit

Over watering is a common mistake in the first year. New plants do need regular water while their roots settle in. After that, a healthy bed with good soil and mulch can usually be watered less often.

Many gardens get more water than they want. The Water Corporation says most Perth gardens need 10 millimetres of water twice a week in summer. Perth has a dry summer and sandy soils, so that figure will not suit a garden in Hobart or Brisbane.

Your local water utility or council will have local guidance and any watering rules. Follow those first. Then adjust to what your own soil and plants show you.

• Improve the soil before you plant.
• Group plants by water needs.
• Mulch 5 to 10 centimetres deep.
• Water to need, not to habit.

Lawns and pots

If you keep a lawn, choose a variety that suits your climate. Then size it to the area you really use, so there is less to water. Our guides to laying a new lawn and spring lawn care cover the practical steps.

Pots need their own plan because they hold far less soil than a garden bed. Keep them where you can check them easily and use a good potting mix. Our advice on keeping pot plants alive while you are away is worth a read before summer.

Frequently asked questions

When is the best time to improve garden soil?

The Water Corporation advises preparing soil before planting, preferably in late autumn. In cooler or wetter regions the best timing may differ, so check local advice. Mixing in organic matter early gives it time to start working.

How thick should mulch be?

The Water Corporation recommends 5 to 10 centimetres across the soil surface. Keep it away from plant stems. A chunky mulch works well around shrubs and trees.

Do native plants need no water at all?

No. The Water Corporation says they need less water, not none. Young plants still need watering while they settle in, so check what each species needs. Group them with plants that have similar needs.

What if my soil repels water?

Add organic matter and use a wetting agent, as the Water Corporation suggests. The Water Corporation also notes that mulch reduces evaporation. Together these steps help water soak in and stay in the soil.