Garden & pool

Understanding your garden’s water needs

Three factors combine to determine how much water your garden needs.

  • the type, texture and depth of your soil 
  • the plants you choose and where they're planted
  • the unique environments, or microclimates, of your garden or pool.

A garden that makes the most of its microclimates can survive a hot, dry summer week before it needs additional water. But you'll need good soil and a smart choice of plants. Your soil’s ability to hold water where most roots can reach it has the biggest impact.

By planting fragile plants in protected areas, you can water less and make the most of rainfall. The types of plants you choose and the microclimate also affect how often your garden needs water.

Hands holding soil

Good quality loam soil reduces garden water needs.

Soil types range from pure sand to clay.

Sand can hold very little water. Clay-based soils can hold more water, but your plants will find it hard to get water from the clay. The best soil is loam - a mix of sand, clay and organic matter.

Your soil acts like a rainwater tank. The type and depth of your soil controls how much water it can store. For example, the best loam soil that's 30 cm deep can hold up to 25 mm of water. The same depth of sandy soil or clay soil will hold just 5 mm of water.

Slopes mean water can run off before the soil has a chance to absorb it. Applying too much water, or applying it too quickly, can also cause run-off. This may also cause erosion.

Plants in a deep loam soil have a much better chance of surviving a week-long heatwave without extra watering compared to the same plants in sandy soil.

Residential garden with flowers, wall and rainwater tank

Select plants that suit the microclimate in your garden.

Most gardens have different climate conditions in different areas. These areas have their own microclimate. 

What are the common microclimates in Sydney gardens?

  • The southern sides of houses are cooler, shadier and less exposed to the sun and hot, dry winds.
  • The northern and western sides of homes are typically hotter and get more sunlight throughout the year.
  • Back gardens are often more shady, wind protected and therefore cooler than front gardens.
  • The areas under trees are more shaded and sometimes more wind protected than areas in an open space, eg the middle of a lawn.
  • Lawn and garden areas next to paths and roads (especially those with black surfaces) are likely to be a few degrees hotter all year round and also after the sun sets.
  • Narrow gaps between homes or buildings will often have a shady, wind tunnel effect.

Place plants in a microclimate closest to their natural habitat. You'll reduce your garden's water needs by making the most of your plant’s natural abilities. 

Two people planting a plant in a residential garden

Select plants that suit your garden and group plants with similar water needs together.

A plant’s water needs relate to where they grow naturally.

You can’t always re-create the original soil and climate conditions, but understanding them will help you choose the best combination of plants and location.

Plant labels normally refer to the plant’s original habitat. Adjust the advice to suit your local conditions.

Planting a shade-loving fern in a sun and wind exposed position will probably kill it, even if you water it often.

However, a tough, sun-loving plant native to a warm, dry climate will thrive in the same position with little or no extra water.

Our plant selector helps you find plants that suit your garden’s style and local climate conditions.

Person watering garden with hose and nozzle

Choose plants suited to your  garden's microclimate so you don't need to water as often.

Understanding your pool's microclimate

The type of microclimate around your pool will affect how much water is lost though evaporation.

A pool that's exposed to the wind will lose much more water and heat than a sheltered, wind-protected pool.

Person unwinding a pool cover

Pool covers reduce evaporation and heat loss.

The amount of water you use to top up your pool each year can be as little as a few thousand litres to more than the total volume of your pool.

Because pool water can be lost through splashing and evaporation, it can be hard to tell if there are leaks or other issues causing water loss. 

How can you improve water efficiency in your pool?

  • Use a pool cover - it's the best way to reduce evaporation and to save heat and chemicals.
  • Shield your pool from wind using thick hedges or solid fences.
  • Keep the water level half way up the skimmer box - you'll take advantage of rainfall and ensure the filter can easily collect surface debris.
  • Limit backwashing to a couple of minutes.
  • Act quickly if you suspect you have a leak in your pool or its pipes or fittings. Leaks waste a lot of water and small problems can get much bigger over time.
  • Check the weather forecast before topping up your pool (or watering your garden). If it's going to rain, let nature do the job for you!