How to Make Your Own Compost

Turning food scraps and organic garden waste into compost has many fantastic benefits, including:

Compost is a rich source of organic matter and adding this to soil improves soil quality and soil structure, as well as promoting plant growth and garden vitality.

Compost encourages more earthworms and beneficial soil microorganisms into your garden.

Composting your own organic waste reduces the amount going to landfill, helps minimise greenhouse gas emissions, and reduces leachate, which can pollute land, groundwater and waterways.

The rich organic matter in compost acts like a sponge and enables the soil to retain more moisture and nutrients.

Composting organisms require four equally important components to work effectively and create the best possible compost - nitrogen, carbon, oxygen and water.

Green ingredients will supply your compost pile with nitrogen that feeds microorganisms and helps them break down carbon. Nitrogen-rich materials are often green and wet such as kitchen waste and scraps, fresh lawn clippings and plant material such as soft leafy prunings and weeds pulled from your garden.  Every compost pile needs green ingredients, but if all you have is green material, your pile can turn stinky and wet. Too much green material can lead to a rotting pile instead of a composting pile.

Brown ingredients will supply your compost pile with carbon for energy (heat). Carbon-rich materials are often woody and include autumn leaves, branches, woody hedge clippings, straw, wood shavings (untreated), cardboard and newspaper. Carbon is essential, but again, too much has its consequences. If you have a pile with mostly prunings from your hedge and other woody material, the pile can take years to break down.

Oxygen is needed for breaking down the carbon, facilitating the decomposition process. Oxygen can be 'added' to the compost by regularly turning all the ingredients. Use a fork or a specialised compost aerator.

 If your compost becomes starved of oxygen (anaerobic composting), then it starts to produce greenhouse gases - so it's important to get air into your compost heap.

The mix of compost materials should be moist, but not soaking wet, to maintain microbe activity without causing anaerobic conditions.

The ideal ratio of Carbon to Nitrogen (C:N) is 30:1 (30-parts carbon material to 1-part nitrogen material).

Good compost is produced by blending compostable materials like leafy 'green' matter with harder 'brown' matter. 'Green' matter includes grass clippings, kitchen scraps, and soft green prunings. 'Brown' matter is shredded woody branches, dry leaves, straw and shredded newspaper.

Try to add brown and green matter in layers, not making any layer too thick. If you put in too much green matter, the compost may go sludgy and smelly. Too much brown matter and it won't break down quickly. With a good balance of the two, composting will proceed quickly.

Finally, the addition of some Yates Dynamic Lifter Soil Improver & Plant Fertiliser and a small amount of soil will encourage the introduction of composting microorganisms and provide them with additional nutrients. This will promote the breakdown of the material and better finished compost.

• Vegetable scraps and food waste
• Fallen leaves (in layers)
• Dead flowers
• Weeds
• Grass cuttings in layers
• Coffee grounds
• Tea leaves and tea bags
• Soft stems
• Old potting mix
• Egg shells
• Wood ash (in moderation)
• Old, shredded and damp newspapers and cardboard
• Used vegetable cooking oil
• Sawdust (not from treated timber)
• Animal manure (from chickens, sheep and cows)

Avoid adding:

• Diseased plants
• Metals, plastic, glass
• Pet waste, such as dog and cat droppings, can be composted separately in a special composting unit or worm farm
• Large branches
• Weeds that have seeds or underground stems
• Glossy magazines
• Fat
• Meat scraps and dairy products

To make sure your compost is decomposing as fast as it can, follow these tips.

Make sure you set up the compost correctly (see How to Make a Compost).

Use the right ingredients (see Compost Ingredients) and get the balance of ingredients (see Getting the Right Balance).

Add soil and manures to help introduce microbes and food for microbes.

Add garden lime or dolomite if the mix has become too acidic from excess "green material".

Temperature is important for speeding up the composting process. In warmer weather, the compost will break down faster. In winter the compost will slow down dramatically - insulate the exterior with bags of leaves or similar.

Place your compost heap or bin in a well-drained outdoor space that has some shade. Too much sun will dry out your compost.

Start with a layer (at least 15 cm thick) of coarse carbon material such as twigs or mulch, which is used to improve drainage and aeration.

Then follow with a layered A.B.C.D. system using these materials (see What Goes in a Compost for details):

A. Nitrogen material

B. Carbon material

C. Water - spray water after each layer to keep the heap moist but not wet.

D. Soil - sprinkle with soil and Yates Dynamic Lifter Soil Improver & Plant Fertiliser. Adding soil adds microbes that help the compost break down more efficiently. Adding Yates Dynamic Lifter provides the microbes with a rich source of nutrients.

Hint: Make sure your compost ingredients are cut into small pieces so they break down more rapidly.

Aerate your compost weekly by turning over all the ingredients with a garden fork or compost aerator. Aerobic composting will help all the material break down faster and prevent unpleasant odours.

For elevated compost tumblers, rotate them each week to mix all the ingredients around and improve aeration.

Compost bins or piles that heat up are working correctly. Heat is created as the microbes start to break down the ingredients. High temperatures in the compost (around 60 – 70 degrees Celsius) also help to kill weed seeds and plant pests and diseases.

When the compost no longer contains any recognisable material, the compost is completely decomposed and is ready and safe to use in the garden.

Depending on the mix of ingredients and temperature, compost can take anywhere from 6 weeks to 6 months to be ready.

Mix your homemade compost into garden beds before sowing or planting or apply around the root zone of established plants.

Slaters help break down organic matter and so are beneficial in your Compost heap. There's no need to remove them.

Ants may indicate that the compost is too dry or the mix of ingredients is incorrect. Ensure the compost bin or pile is kept moist and there is the correct blend of nitrogen and carbon-based ingredients. Too much woody and dry material can encourage Ants.

An excess of green (nitrogen) material or overwatering the compost bin can cause the mix to become wet. Include more brown (carbon) materials in the blend and reduce the amount of water applied.

Light brown grubs in compost are likely to be Soldier Fly larvae. These insects help break down organic matter and so are beneficial in the compost bin.

Rodents, such as Rats and Mice, may be attracted by the organic materials in the compost. In compost bins and tumblers, ensure the lids are kept closed to limit rodent access. Regularly turning and aerating the compost ingredients can help deter rodents. And avoid adding ingredients like full eggs, meat and dairy into the mix. If rodent problems persist, consider placing a rodent trap near the compost bin.

Avoid adding too many Gum Tree (Eucalypt) leaves as these can take a long time to break down. They can also have compounds in them that are toxic to plants and microbes. However small amounts of gum leaves, used throughout the compost pile, are fine. 

Citrus peel breaks down slowly, however is fine to include in your compost mix.

Yes, Onion skins can be used as an ingredient in compost. 

Yes, there are bench-top composting units that are ideal for using indoors.