Composting

Making your own compost is a great way to use garden and kitchen waste.  Capturing leaves, bark and grass clippings that might otherwise go down the stormwater drain means your garden not only benefits from the compost you make, but you also helps keep our waterways healthy. Leaves, bark, grass clippings and other organics decompose taking oxygen from the water and releasing phosphorous. Phosphorous feeds alga which results in blue-green algae (a toxic bacteria).In large numbers blue-green algae can be dangerous to humans and animals.

To get started

Green compost binChoose a site. Remember that you will be more inclined to put your waste in the compost bin if it is readily accessible and not tucked away in the bottom corner of the garden. A shady site favours composting systems where worms and other soil living organisms are going to be active in breaking down waste. Other systems, designed to treat food wastes like meat or animal faeces are best put in a sunny spot to allow the bin to heat up to a good working temperature. Whichever site you choose it should also have good drainage and room to stockpile dry material that is needed to build your heap.

Choose a container. There are many composting systems that are relatively cheap (compared with a bag of compost from the garden centre) and sized to suit every domestic situation from a unit balcony to a large rural residential garden. Some systems work as tumblers, others use high temperature (‘Green Cone’), whilst others require turning, forking or agitation. You can also get creative and build your own from second hand materials.

Choose the right ingredients. All composting systems, apart from tumblers and Green Cones, are built using layers of organic matter that are either nitrogen or carbon rich, assisted by material which regulates the system.

There are four key components of a healthy compost system: aliveness; diversity; air and moisture.  All four components need to be present and the system monitored to ensure they are all in the right balance.

  • Aliveness: Compost heaps are a living system full of billions of microbes, fungi, bacteria, worms and insects that are working their way through breaking down the heap into humus.
  • Diversity: Just as the heap is full of a diverse range of creatures, so what you add to your heap needs to be balanced as detailed in the feeding plan below.
  • Air: The better the air circulation the less your heap will smell. This means aerobic rather than anaerobic bacteria are at work in your heap. Regular addition of coarse material helps with air flow as well as agitation or turning.
  • Moisture: A moist heap means the organisms at work are alive and healthy and break the heap down faster.  Make sure the heap is not soggy, just moist is best.

This table shows what you need to do to keep these four factors in balance and your compost heap healthy and productive.

Daily ingredients (nitrogen rich)

Weekly ingredients (carbon rich)

Occasional ingredients

Fresh grass clippings

Fruit and vegetable scraps

Bread

Human and animal hair

Vacuum dust

Manure

Weeds

Coffee grounds

Tea bags and leaves

Tree prunings

Dry grass clippings and leaves

Straw and hay

Cane mulch

Dead flowers

Bark

Paper and cardboard

Wood ash

Lime

Dolomite

Blood and bone

Dynamic lifter

Soil

Egg Shells

Harvesting and using your compost

Homemade compost binIt should take three to four months for your compost to be ready. Composting in the Canberra region over winter will take a little longer, although a healthy, active heap will keep warm even through the coldest winter.

Compost can be dug directly into the soil or applied as a surface mulch. It is great as a lawn top-dressing or around plants in the vegetable garden. Soaking a sack of compost in water to make compost tea, turns compost into liquid fertiliser that gives anything in the garden a nutrient boost.

Want to know more?

There is a lot of advice available online about composting. Local garden centres, gardening groups and environment and sustainability groups provide advice and run courses on composting.

By being an effective composter, you are making a difference to our waterways, diverting waste from landfill and giving your garden a boost.