Soils for nature

Soil in your backyard, garden pots, and courtyards is rich with bacteria, fungi and small invertebrates that help keep it healthy. Healthy soil means healthy plants, which provide places for our wildlife to live.

It’s important to know what sort of soil you have in your garden. This can help you work out what plants will grow best.

Sydney has two major soil types:

  • sandy soils, which come from Hawkesbury sandstone
  • clay soils, which come from shales or volcanic rocks.

Some soils may be a mix of the two. Some plants only grow well on one of these soil types, while others can adapt and will grow on both. 

Before you choose plants for your garden find out what varieties suit your soil type. Read the label before you buy a plant, as this usually includes information on the soil type suited to that plant.

Look after your soil and what lives in it

Front part of a black millipede insect crawling across a log.

Healthy soils are home to invertebrates like insects and worms that: 
  • help aerate our soils
  • help water to penetrate more deeply
  • eat fallen plant matter and convert it into nutrients for plants.

Microorganisms, including bacteria, fungi and tiny worms, are also essential for healthy soils. These organisms:

  • help plants take up nutrients or change nutrients into a form plants can absorb
  • help break down dead plant or animal matter
  • reduce the likelihood of plant diseases.

Image of a pair of hands in gardening gloves planting in rich dark soil.

What’s your soil type?

Sandy soil

This soil type:

  • drains quickly
  • has good aeration
  • is usually low in nutrients
  • requires water and fertiliser more often than clay soils
  • suits many Australian native plants.

If your soil is sandy choose native species such as grevilleas, banksias, hakeas or acacias that can extract nutrients from poor quality soils. If you want to grow plants that need more fertile soil, add well-rotted animal manure, compost or leaf litter to improve nutrient levels. Find out more about recycling household food waste into compost and worm farms.

Clay soil

This soil type:

  • drains slowly
  • has poor aeration 
  • is usually high in nutrients. 

You can improve clay soil by adding well-rotted organic matter, and gypsum, which breaks up the clay and makes it easier to work with.

Healthy soil will have a balance of organic matter, invertebrates like worms and insects, microorganisms and fungi.

It’s easy to keep your soil healthy:

Part of a vegetable patch showing compost on soil, mulch and lettuce growing.

  • Mulch your soil with leaves, grass and other types of organic matter, but don’t mulch with pine bark – the invertebrates that break down organic matter don’t like it.
  • Avoid using pesticides, fungicides and herbicides – they also kill the good invertebrates, fungi and microorganisms.
  • Limit how much you compress or stand on your soil as this can make it difficult for plants to grow. 
  • Turn compressed soil with a fork to aerate it and break up large clumps. 
  • Don’t let your soil dry out too much, it can become hydrophobic and repel water so it can’t soak in.

Three golden-coloured mushrooms growing out of leaf litter after rain.

Fungi – including mushrooms, toadstools and bracket fungi on logs – are important organisms that help maintain soil health. 

Many fungi work in a symbiotic or mutual relationship with plants to help them take up nutrients and germinate seeds. In return, fungi get to access the nutrients in the plant’s roots. 

Avoid using fungicides to control problems like powdery mildew or black spot. You’ll kill the good fungi as well as the ones you don’t want. This means less healthy soil and plants. Dispose of infected leaves in a bin, don't compost them.

Record fungi you see and help put Sydney’s fungi on the Australian fungi map.