Good soil is the base of every healthy garden. Compost is one of the simplest ways to improve it. It turns kitchen scraps and garden clippings into dark, crumbly organic matter. You can dig it into beds or spread it on top as mulch.
Making compost at home is not complicated. It mostly comes down to the right mix, enough moisture and some air. This guide draws on home composting advice published by local councils. It covers what to add, what to leave out and how to fix common problems.
Why compost is worth the effort
Composting relies on natural decomposers. The City of Port Phillip lists bacteria, fungi, worms, millipedes and other tiny organisms as the workers. They break down food and garden waste into reusable organic matter. The result improves soil condition and feeds your plants.
It also keeps organic waste out of landfill. The City of Monash notes that food and garden waste in landfill produces methane, a greenhouse gas. Home composting turns that same waste into something useful. It is a practical habit for any home with a bit of outdoor space.
Choosing a compost system
There are several ways to compost, and the best one depends on your space. A compost bin suits a backyard and accepts larger pieces, although it breaks down more slowly. A tumbler or barrel speeds things up if you chop material small and avoid overfilling it. A simple open heap works for garden waste only.
Small spaces have options too. Moreton Bay Regional Council suggests worm farms for balconies and garages. Monash describes bokashi as a good fit for apartments, although the fermented waste must be buried or added to a compost bin to finish breaking down. If you have no room at all, a neighbour who composts may welcome your scraps.
Getting the mix of greens and browns right
Compost needs two kinds of material. Greens are rich in nitrogen and browns are rich in carbon. Moreton Bay advises covering each layer of food waste with carbon materials. This simple habit does a lot to keep the heap balanced. The council lists these as common ingredients:
- Greens: fruit and vegetable scraps, coffee grounds, tea bags without plastic mesh and small amounts of fresh grass clippings.
- Browns: dried leaves, dried grass, straw, mulch, cardboard, shredded paper and newspaper without glossy pages.
- Other browns: thin broken twigs, toothpicks, timber skewers and paper towel.
Size matters as much as the mix. Smaller pieces break down faster, so cut or mulch garden waste before adding it. Moreton Bay notes that broccoli and corn stalks, apple cores, citrus skins, eggshells and prunings slow the process. Chop them up or add them sparingly.
What to leave out of the compost
Some materials cause smells, attract pests or spread problems back into the garden. Moreton Bay advises against adding dairy, meat scraps, bones or pet faeces. Plastic, treated timber and vegetable fats or oils should also stay out. These items either do not break down properly or draw unwanted visitors.
Weeds and diseased plants are on the same list. So are plants that have been sprayed with pesticides. Composting weeds can spread their seeds back through your beds when you use the finished compost. Our guide to weeding your garden like a professional has ideas for dealing with them in other ways.
Moisture and air
A healthy heap should feel damp all the way through. If it is too dry, add water until it is. Moreton Bay suggests leaving the lid open during rain. If it is too wet and smells, add more browns.
Air is the other half of the equation. Turning the heap more often speeds up breakdown. Tumblers need regular rotation for the same reason. If turning is hard, a pipe with air holes set in the centre of the bin helps air move through.
Fixing common compost problems
A bad smell usually means the heap is too wet or short of air. Moreton Bay recommends adding browns, turning more often and mixing in garden lime or dolomite. Slow breakdown usually points to material that is too dry, too large or lacking active ingredients. Add water, chop pieces smaller and mix in food waste, comfrey or manure.
Pests are another common complaint. Moreton Bay suggests covering maggots with garden lime. It also notes that maggots and cockroaches can help breakdown if you can live with them. Mice and rats tend to follow excess bread or grains. Covering food with browns, turning often and placing fine wire mesh under the bin all help keep them away.
Using worm farms alongside a bin
A worm farm makes a good partner to a compost bin. Monash explains that worm farms produce worm castings and a liquid often called worm tea. The castings can be dug into the garden. The liquid can be diluted to water plants.
Worms have their own preferences. Moreton Bay advises keeping onions, chilli and citrus out of a worm farm. It suggests diluting the worm liquid at about one part to ten parts water before using it as fertiliser. Feed worms small amounts and see how quickly they get through it.
Using finished compost in the garden
Finished compost should look dark and crumbly, with little sign of the original scraps. Dig it into garden beds before planting or spread it on top as a mulch. Monash notes that both approaches work. Bed preparation is a good time to add it, as the soil is already open.
Compost works well when you are planting new areas or refreshing tired ones. Our tips on planting around pools and lawns pair well with a fresh load of compost. If you are planning a bigger change, start with the landscape design style you want and build the soil to suit those plants.
Not everyone has time to manage beds and soil through the year. A good maintenance team can prepare beds, add organic matter and keep weeds under control. Our article on using professional landscapers explains what that support can look like. Either way, healthy soil makes every other part of the garden easier.
For more detail on local services, read the Moreton Bay Regional Council composting guide. Many councils publish similar advice for their own area. Some also run home composting programs or community compost hubs.
Frequently asked questions
What is the difference between greens and browns?
Greens are nitrogen rich materials such as fruit and vegetable scraps and coffee grounds. Browns are carbon rich materials such as dried leaves, straw and cardboard. Covering each layer of food waste with browns keeps the mix balanced.
Why does my compost smell?
A smelly heap is usually too wet or short of air. Add more browns and turn it more often. Garden lime or dolomite can also help.
Can I put weeds in my compost?
Council advice is to keep weeds and diseased plants out. They can spread seeds and disease back into the garden. Plants sprayed with pesticides should also stay out.
Is a worm farm better than a compost bin?
Neither is better in every case. Worm farms suit small spaces such as balconies, while bins suit backyards with garden waste. Many households use both.
