A beginner’s guide to composting

Put simply, composting breaks down organic matter, which is anything that was once living. The nutrients are recycled to help grow healthy new plants.

Why should we keep compostables out of landfill?

Apart from being a wasted resource, when organic waste is sent to landfill it rots and releases methane, a greenhouse gas with 21 times the global warming potential of carbon. Currently in SA, around 40% of waste placed in landfill bins is food and other compostable items. It’s a problem that every household can help tackle.

It’s easy to start composting at home.

We break it down for you in this beginner’s guide.

Compost heap, bin or tumbler?

Let’s keep it simple. If you have a small to medium size garden, then a decent sized compost bin that sits on the soil is the best way to get started and keep composting for years to come.

One bin good, two bins better.

With at least two compost bins, you can have one taking your scraps while another sits and matures. But you won’t need a second bin until your first one is full, which could take months. One is a great start.

Make it pest-proof.

You want to feed your soil, not a bunch of rats and mice.

The most common type of compost bin, a heavy-duty plastic cylinder with an open bottom and a lid, is easy to pest-proof.

Clear a flat spot of earth, lay down a piece of sturdy wire mesh and place your bin on top. Check for gaps.

Wrapping the wire up around the edges makes it extra secure. Your mesh should be fine enough to stop mice but open enough to let in good critters like worms. Approximately 1cm grid is ideal.

That’s it. Now fill it up!

It’s good (but not essential) to start with a base layer of something that helps aeration and drainage, like twigs or wood chips.

The golden rule of composting is to balance your ‘green’ and ‘brown’.

‘Green’ is anything fresh like food scraps, lawn clippings and green garden prunings.

‘Brown’ is old, dry material like dead leaves, wood chips, straw and plain brown cardboard.

Aim for at least 50/50 brown to green. Too much green and you’ll end up with a smelly mush. Autumn leaves are an abundant and free source of brown material.

Smaller pieces compost more quickly. Give your compost a helping hand by cutting up big stems, crushing eggshells and so forth.

Turn, turn, turn.

A worthwhile investment is a corkscrew-shaped compost turner.

Mixing and aerating your compost helps maintain a healthy heap that breaks down faster.

Turning once a week or so is helpful but not a deal-breaker.

If you have a good green/brown balance, compost is very forgiving.

Note: turning and handling compost can release bacteria and fungal spores. Use common sense, wear a dust mask if you think you’re at risk, and wash your hands well afterwards.

Keep it damp.

In hot weather you may need to add water to your compost, to keep those beneficial microbes and insects thriving.

When the compost bin is full, let it rest for about three months.

Keep the lid on and forget about it for a while. This is a great time to start your second compost bin. After a few months, you’re ready to shovel up that ‘black gold’ and dig it into your garden. Congratulations, you made compost!

But my compost doesn’t look like the photo!

In reality, nobody’s compost looks exactly like photogenic, crumbly soil. Some things take longer to break down. You can expect to still see things like eggshells, avocado skins and pits and pieces of compostable bags. Just dig them into your soil and they will continue to break down and enrich your garden.

Surprising things you can compost:

• Egg cartons
• Hair and nail clippings (pet and human)
• Old natural fibre fabrics (e.g. worn pure cotton or linen bed sheets – cut into small pieces, avoid seams which may be sewn with polyester thread)
• Brown cardboard (remove any sticky tape or staples and tear into pieces)
• Cardboard toilet rolls (rip up)
• Tissues and paper towel
• Cotton buds with wooden or paper stems
• Shredded office paper
• Certified compostable packaging (some needs commercial composting conditions but it’s usually worth a try at home).

Avoid these:

• Animal products (meat, bones, dairy etc.) – small amounts may be fine but use your council green waste bin if you’re unsure
• Fats and oils
• Plastic fruit stickers, rubber bands, other produce labels
• Glossy paper and cardboard that seems to have a coating
• Treated timber or its sawdust
• Diseased plants and weed seeds
• Pet poo (there are specialist worm farms available, or use your council green waste bin).

Ask yourself: would I eat a vegetable that grew out of that? If not, don’t put it in your compost bin.

Compost heaps for large gardens.

To compost large amounts of garden waste, you can build a compost heap.

Ideally this will be at least one cubic metre in volume of green and brown layers, which allows enough bulk for ‘hot composting’ to occur.

Biological processes build up heat which accelerates the composting process and can even kill weed seeds.

Unless your large compost heap is contained in a rodent-proof structure, do not use it for food scraps, or you might find yourself attracting unwanted guests.

No garden or space? Put all compostables in your green bin.

If you don’t have a garden or your space is really too small for a composting system, you can put your organic waste in your green council bin to be collected and turned into compost at a commercial facility. Thanks for helping keep compostables out of landfill.

If you live in a fruit fly outbreak area in South Australia, please check the latest advice before composting restricted fruit and vegetables at fruitfly.sa.gov.au

Making the most of your back yard? You might like to check out our stories: How to attract native bees and How to make a raingarden.