Composting down our organic waste reduces the impact on our landfills and it's great for the condition of our garden soil.
Why should I compost?
Composting makes good environmental sense. It's cheaper than taking organic material and garden waste to landfills. Compost also provides an excellent material to enrich the garden and encourage plant growth.
How do I make compost?
Composting can be done right in your own backyard in a sheltered area.
Build your own worm farm
Worm composting is an easy, cost effective way of recycling organic kitchen waste. A worm farm is a mini composting factory. It enriches your garden, helps the environment and anyone can do it. All you need is a container, worms, bedding and your organic waste and you’re away!
Find out more about how to create your own worm farm
Setting up a bin
- Good drainage
- Sheltered area
- A garden hose within reach
The compost heap or container should sit directly on the soil.
The compost bin can be made at little cost. Your options for making the container are:
- For an effective and flexible homemade container, wrap wire netting around wooden stakes and line with cardboard or newspaper.
- Stronger bins can be made from wood, bricks, or concrete blocks. You'll need to add holes for air and ensure ready access from the front.
- You can make a good compost container from shipping pallets.
- Alternatively, purchase a commercially made bin from a garden centre or hardware store.
Five simple steps of compost making
Before positioning the bin, fork over the soil to aid drainage and encourage worms. Ensure bin is aerated through ventilation openings or raise the bin on a few bricks.
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Place a 10-15cm layer of coarse twiggy materials (materials from a previous heap may be used) at the bottom of the bin to ensure good drainage and entry of air.
Add alternating layers of "browns" and "greens" at a ratio of 50:50. "Greens" are anything that is fresh and juicy (nitrogen-rich), such as kitchen scraps, grass clippings or fresh garden waste. "Browns" are anything that is dry and fluffy (carbon-rich), such as scrunched up paper (eg, newspaper, paper towels, shredded office paper), dried grass clippings, hay, straw or dry autumn leaves.
Continue to build the compost heap with alternating layers, as material becomes available. When the bin is full, cover and leave the heap to mature. If you regularly turn the compost heap it will take three to four months to mature, but without turning, it will take nine months to a year. Turning once a month will aerate the heap and mix the decomposer organisms through the waste material.
To speed things up and improve nutrient content, you can add layers of poultry litter or animal manure. Seaweed, soil, or your own mature compost can be used if animal manure is not available. Alternatively, use a few handfuls of blood and bone, sulphate of ammonia fertiliser or a compost starter kit available from garden shops.
How do I use compost?
- When mature, spread three centimetres of compost and mix into topsoil. Any remaining stalky material can be removed and recycled into your next compost heap.
- Mature, sifted compost mixed with two parts topsoil and one part sand makes an excellent seed raising or potting mix.
- Compost gives newly planted trees and shrubs a good start. Mix one or two buckets of compost into the soil prior to planting.
Then sit back and relax and watch your garden flourish, knowing that nature's recycling system is hard at work.
- Compost shouldn't be too acidic. Make sure you add enough brown material to ensure airflow. Try a light sprinkling of dolomite or lime every few layers.
- To speed up the process, chop or shred materials into small pieces.
- Aerate your compost regularly. Air is essential for odour-free composting.
- Dampen your heap regularly in summer to maintain a consistency of a squeezed out sponge: moist but not soggy.
- Compost is mature when it's darkened and has a crumbly soil-like texture with a pleasant odour.
- If offensive odours (such as "rotten eggs") are produced, turn your compost heap to aerate it.
- The best compost needs the right mix of carbon (dry stalks or leaves) and nitrogen (green matter, fruit or animal manure).
Great things to compost
- Vegetable/fruit scraps or peelings
- Tea leaves
- Soft garden debris such as leaves, lawn clippings, weeds (if they haven't gone to seed)
- Untreated wood ash, sawdust or straw
- Animal manures
Things to avoid
- Meat, fish, fats or cooking/salad oils
- Wood, bones, tin, glass or plastic
- Diseased plants
- Plant foliage with chemical spray residue
- Toxic material
- Treated timber - don't use it for constructing your compost bin!
Weeds in your compost
Noxious weeds like oxalis, live twitch and convolvulus need to be treated before you can compost them - otherwise they'll take over your garden once you spread that compost out on the soil.
Either submerge weeds in water for 3-4 months or leave in a black plastic bag in the sun for a few months to 'cook' or 'drown' the weeds. The resulting sludge can be added to the compost.
It's okay to compost a little bit of grass and other weeds - avoid seeds and thorns if you can, and mix your garden waste in with other material so your bin doesn't get too acidic.