Why should I compost?
Composting organic waste reduces the impact on landfills. It improves the condition of garden soil, enriching gardens and encouraging plant growth.
Its cheaper than taking organic material and garden waste to the landfill, so you'll save money.
You can make compost right in your own backyard with minimal space, effort, knowledge. All you need is:
- Good drainage
- A sheltered area to sit the heap or container on the soil
- A garden hose.
How to make compost - 5 simple steps
Before you start
You'll need to source a bin or container that the compost will go into. Here are some ideas:
- Wrap wire netting around wooden stakes and line it with cardboard or newspaper. This is an effective, flexible home made option.
- Make a stronger bin out of wood, bricks, or concrete blocks. Remember to add holes for air and make sure it can be easily accessed from the front
- Make a compost container from shipping pallets
- Buy a pre-made bin from a garden centre or hardware store
Step 1 - Aerate
Before positioning the bin, fork over the soil to help drainage and encourage worms. Aerate the bin with ventilation openings (holes) or raise it on a few bricks.
Step 2 - Base layer
Place a 10-15cm layer of coarse twiggy materials at the bottom of the bin so it can drain, and air can come in. You could use materials from a previous compost heap.
Step 3 - Alternate layers
Add alternating layers of "browns" and "greens" at a ratio of 50:50.
Green material is fresh, juicy and nitrogen-rich:
- Kitchen scraps
- Grass clippings
- Fresh garden waste.
Brown material is dry, fluffy and carbon-rich:
- Scrunched up newspaper
- Paper towels
- Shredded office paper
- Grass clippings
- Hay or straw
- Dry autumn leaves.
Step 4 - Keep building
Keep building the compost heap by alternating layers as you get material.
- If you turn the compost heap regularly it will take 3-4 months to mature.
- Without turning, it will take 9 months - 1 year.
- Turning once a month will aerate the heap and mix the decomposer organisms through the waste material.
Step 5 - Speed up the process
To speed things up and improve nutrient content try adding some of the following:
- Layers of poultry litter or animal manure
- Seaweed, soil, or your own mature compost if animal manure is not available
- A few handfuls of blood and bone, sulphate of ammonia fertiliser
- A compost starter kit (available from garden shops).
How do I use compost?
- When mature, spread three centimetres of compost and mix into topsoil.
- Remove any stalks and recycle it into your next compost heap.
- Mature, sifted compost mixed with two parts topsoil and one part sand is great for 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 before planting.
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 by turning it. Air is essential for odour-free composting, so aerate it if starts to smell bad (eg. like rotten eggs).
- Dampen your heap regularly in summer. It should have the consistency of a squeezed out sponge - moist but not soggy.
- Compost is mature when it's dark and has a crumbly soil-like texture with a pleasant odour.
- The best compost needs the right mix of carbon (dry stalks or leaves) and nitrogen (green matter, fruit or animal manure).
What items can I compost?
Here are some good things to put in your compost heap:
- 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 manure
What items can't I compost?
Avoid putting these in your compost heap:
- Meat, fish and bones
- Oil and fat (including cooking and salad oil)
- Tin, glass or plastic (recycle instead)
- Diseased plants
- Plant foliage with chemical spray on it
- Toxic material
- Treated timber - don't use it for constructing your compost bin.
Weeds in your compost
Treat noxious weeds like oxalis, live twitch and convolvulus before composting them. If you don't, they'll take over your garden once you spread the compost on the soil.
To 'cook' or 'drown' the weeds, submerge them in water for 3-4 months or leave them in a black plastic bag in the sun for a few months. Add the resulting sludge 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.
Build a worm farm
Another composting option is to build a worm farm. This works like a mini composting factory and is an easy, cost effective way to recycle organic kitchen waste.
It enriches your garden, helps the environment and anyone can do it. All you need is a container, worms, bedding and organic waste.