Back to basics: How to Make Compost

What’s the answer to good soil? Compost.

Thousands of years ago, the Chinese discovered that composting—recycling organic farm waste—was vital for replenishing soil nutrients lost through leaching and human activities. Today, composting is not just a good idea but essential in both rural and urban areas. As population and pollution strain our soils, composting remains a cost-effective and environmentally sound solution.



Home-garden compost transforms organic waste into a cost-effective, nutrient-rich material teeming with beneficial microbes. This compost enhances soil structure, aids in water and fertiliser retention, and enriches the soil with organic nutrients and living biomass. It is particularly effective at improving both sandy and clay soils.



The dictionary defines compost as a ‘mixture of organic substances’, therefore a compost heap or bin won’t work with only cut grass, kitchen scraps or fallen leaves alone.

What goes in, what stays out

IN-gredients

Lawn clippings, leafy weeds (without seeds or bulbs), prunings, spent flowers, vegetables, kitchen scraps, shredded paper, tissues, eggshells, egg cartons, washed seaweed, used kitchen paper, paper tea bags, citrus peel and onion scraps.



Fallen leaves (eucalyptus, frangipani, plane tree and oak leaves) benefit from being shredded before adding to your compost. You can even include decomposing cotton T-shirts and other natural-fibre clothing. Animal and human hair waste are rich in nitrogen. Burnt wood and fireplace ash are rich in lime and potassium, while coffee grounds should be used in moderation.



OUT-gredients 

Avoid fish, dairy or meat scraps as they can attract rodents and introduce undesirable bacteria. Domestic animal droppings should be excluded for the same reasons. Refrain from including charcoal, coal ash, ash that includes incinerated plastics, treated pine wood ash, and cigarette butts as they can be harmful to your compost and garden.

The right balance

When adding material to your compost, maintain a 50:50 balance between carbon-rich "browns" (such as autumn leaves, twigs, sugarcane mulch, and straw) and nitrogen-rich "greens" (like vegetable peelings, fresh prunings and cut grass). This balance ensures a stable carbon-to-nitrogen ratio.



Avoid overloading your compost heap with a single type of material, such as lawn clippings or shredded prunings. Keep a bin of shredded autumn leaves, fireplace ash, and shredded paper nearby to add in layers, lasagne-like, as you go.



Using a variety of raw materials introduces a diverse mix of micro-organisms that aid the decomposition process, turning waste into viable compost. These micro-organisms need plenty of air, so it's important to turn your compost regularly to allow for air circulation.



Moisture is also crucial—keep the compost damp but not wet. Over-saturated compost becomes anaerobic, leading to a sludgy, smelly heap that attracts cockroaches and halts decomposition. In wet weather, cover your compost heap to prevent it from becoming too wet.



Moderate heat is necessary for micro-organisms to perform their composting duties efficiently. In hot weather, covering your compost heap helps maintain the optimal temperature for these tiny workers.

Which bin?

You may have seen our multi-bin compost system on television. If you have the space, this method is the best way forward. Even with just two bins, you can efficiently transfer material from one bin to another, promoting air movement, holding capacity, and preventing excess moisture.



There are many designs for multi-bin systems. Some use old pallets with loose boards at the front for easy access, while others use a solid timber frame lined with wire mesh and a front gate to keep rodents out. Our system includes a wire top for added protection.



The ideal setup involves a three-bin system used in rotation. Bin 1 is for layering new materials, Bin 2 is for transferring materials from Bin 1 once it’s full, and Bin 3 is for resting materials from Bin 1 after it’s been transferred. If you have the time and energy, you can further transfer partially decomposed material from Bin 2 to Bin 3. Alternatively, you can turn the contents of Bin 1 two to three times over 7-8 months, then transfer it to Bin 2 and turn it once. After 9-10 months, you’ll have excellent compost.



Our bins are not placed on a concrete pad, which would have been ideal. Instead, we lined the bottom with wire mesh to exclude rodents, and also keep the top covered too.



I’m not a fan of expensive rotating bins or free-standing, garbage bin-like structures, as they often lack sufficient air circulation and ease of access for making good compost. Over forty years of gardening, I’ve tried many different types, and none have produced compost as easily as the traditional open bin system.

Booster additives 

In the past, I used to sprinkle blood and bone every 20-30cm of material to accelerate the multiplication of soil bacteria and fungal decomposers. However, with the advent of advanced soil biologicals like GoGo Juice and Popul8, the process has become more efficient. I now water these liquid soil biologicals onto my bins every 2-3 months. 



Fresh cow or chicken manure can give a boost to the decomposition process, though it is less effective than other methods. Additionally, adding a sprinkle of agricultural lime or dolomite can further aid in speeding up decomposition. 

The wriggle on worms

Understanding the role of worms in your composting and gardening efforts is crucial for success. There are two main types of worms: compost worms and garden worms. Each type thrives in its own specific environment and will not survive if transferred to the other's ecosystem. 



Compost worms, often available for purchase at garden centres, are excellent for aiding in the decomposition process within your compost bin. However, it's important to note that these worms do not survive once the compost is transferred to the garden. On the other hand, garden worms are adapted to live in soil and play a vital role in maintaining soil health and fertility. Therefore, it's essential to keep each type of worm in its respective environment for optimal results.