Composting guide

Composting guide



Help your vegie patch — and the environment — by composting your organic waste. Here’s how:



Composting is a cost-effective way of providing fertiliser for your vegetable garden and it will reduce the amount of waste that unnecessarily ends up in landfill. By adding your lawn clippings and organic food scraps, you’ll create a nutrient-rich formula to add to your patch to make it thrive.

Keeping your compost in some form of container is best as the rate of decomposition is determined largely by the amount of heat produced inside the heap. There are a few container options for keeping your compost: you can buy a bin from your local hardware or gardening store, build your own in a section of your backyard or buy a rotating barrel, which can help speed up the rotting process. There are even indoor compost bins that have been specially designed for this application.


Do it yourself

You can make your own compost heap by creating three one-metre-square boxes using items you may already have around the yard including old railway sleepers, bricks, treated timber, old pallets or concrete blocks. One section will be used for new material, another for decomposing material and another for ready-to-use compost.

If space doesn’t allow you to create such an elaborate composting area, simply use an old plastic bag or oil drum.


The benefits of worms

Worms play an integral role in garden health and, indeed, the composting process. It’s best to leave the bottom of your composting system open to the earth, so if you’re building your own don’t make a base — this will encourage worms already in the earth to enter your compost area and help break down the organic matter. Worms aerate the soil, mix in the organic matter, improve soil structure and help water penetration. You can usually buy worms from your local gardening outlet or some local councils — it’s a good idea to add some to your compost bin.

Worm castings are great for conditioning the soil as they are high in trace elements and minerals and are pH neutral. You can buy a worm farm or buy a small container of worms.

There are a few easy steps to collecting worm castings from a worm box. Lay out some moist newspaper sheets and already composted material. Add worms and cover with an organic material, such as hessian. Put the box in a spot that usually has an even temperature. After one week, rest some food scraps on the bedding and add more only as the scraps are eaten — do not feed the worms protein such as meats or breads; however, they will eat pet hair, tea leaves and coffee grounds.

Remove the worms and bedding on to a level surface and carefully scrape the castings from the exterior of the box. Give the worms new bedding and start the process again. Keep your worm farm out of the sun as temperatures above 20 degrees Celsius can be lethal.

Use the castings as mulch around your vegie seedlings or add it to your potting mix for container vegetables. You can even use the liquid from the castings — one part castings to 10 parts water — as a fortnightly liquid feed.


What to add to your compost heap

You want to aim to have the right balance of nitrogen (ie food scraps and soft, green garden waste) to carbon (leaf litter and shredded branches). The recommended mix is about 20 parts carbon to one part nitrogen.

Try to put a diverse array of garden waste and food scraps into your bin to create a rich mix. Avoid putting weeds into your compost in case they seed and create problems when added to the garden.

Add water to your compost heap at a rate of approximately 50 per cent. It should be damp, but not wet. Turn the mixture to aerate — this promotes and encourages the addition of more organisms, speeding up the rate of decomposition. It will also ensure that the heap doesn’t become smelly. However, make sure the heap has good drainage so any excess moisture can run out.

The most common things to add to your compost heap are vegetable and fruit scraps, but you can also add tea bags, coffee grounds, egg shells, sawdust, pine needles, straw, ash from fires and fireplaces, grass clippings, newspapers and paper bags. You can even compost the dust from your vacuum cleaner. If you want to add in branches, it’s best to finely chop these using a mulcher.

Do not add the following items to your heap: meat, fish or dairy products, plant bulbs, weeds, diseased plant material, sticks or woody material.

Every now and then add a layer of soil, lime, dolomite or a compost activator to aid decomposition. Be careful not to add too much lime or you may end up with compost formula that’s too alkaline to be used with some plants. Dampen your heap with a liquid fertiliser or seaweed product.



Compost heaps generally look after themselves, but you do need to keep it moist and regularly turn the humus to keep it aerated so that it can decompose properly and to ensure moisture doesn’t cause over-compaction. You can tell if your compost heap is too wet if it becomes smelly. Turn the material so that it can dry out. However, if the material is too free, add a coat of soil to help seal the compost and pack together loose layers.

It’s also imperative to keep a high temperature within the enclosure, so positioning it in full sun is a good idea. Covering the heap will keep it hot and shelter it from rain.


Compost helpers:

Composted material: A shovelful added to your heap will help speed up decomposition.

Comfrey leaves: Accelerate decomposition.

Oxygen: The more you turn your heap the faster it will decay. Aim for at least a weekly turn.

Moisture: Add water whenever you add material to your heap.

From Great Vegie Gardens magazine 1