Kitchen Tips

Easy ways to reduce your food waste by composting at home

Organic food garden and sustainable living expert Claire Mummery gives us the lowdown on turning our food waste into something truly amazing.

Claire Mummery, founder of Grow Inspired, is one of New Zealand's foremost pioneers in regenerative living, nutrient-rich food production and large-scale organic garden development. Her experience in organic practices spans three decades and her areas of expertise include composting, worm farms, garden transformations, and growing nutrient-dense food. We asked Claire to take us through the ins and outs of getting the most from our food waste.
Did you know that approximately 122,547 tonnes of food waste goes to landfill each year in New Zealand? That equates to about $872 million of food! Once in the landfill, it rots and produces a harmful greenhouse gas called methane. With more and more people wanting to grow their own food in their backyard or lifestyle block, it is important to understand the value of composting. By composting we can process all our own food waste and return it to the soil to increase the value of nutrients and microbes in our much-depleted gardens.
I have been composting for the past 30 years and over this time I have tried many different systems on a small and large scale. With so many ways to compost, it sometimes can be hard for the home gardener to understand how to get started. Many people simply give up if something goes wrong or their compost becomes smelly. My aim is to take the complexity out of it and show that even people with busy lives can compost. Two composting systems that I use as my staples are worm farming and bokashi.

Worm farms

For really busy people I recommend a worm farm. They are easy to set up and don't take much maintenance. A worm farm processes all your scraps and paper into a product called 'vermicast' (worm castings) and a magic liquid which is known as 'worm leachate'. In my experience, you can pretty much feed your worm farm anything – from bones, chicken carcasses and veges to paper, teabags and coffee grounds.
Worms process all your household paper, from the cardboard inside toilet rolls to shredded paper from your home office. Some say not to feed them onion skins and citrus, but my advice is that it's usually fine to feed them anything – just avoid anything in excess. The only rule in my experience is that the larger the item, the longer it will take to break down. Therefore, avoid big shells and bones, and make sure you tear up paper and cut your scraps into small pieces. I would also avoid fish bones as these take a long time to break down, and also can remain quite sharp when put in the soil. Instead, I suggest digging a hole and burying these where you intend to plant a fruit tree or a perennial plant.
Vermicast is a valuable addition to soil, helping to promote beneficial bacteria and restore the structure of plants if they've been subjected to harsh weather. Drain off the worm leachate and feed it to plants neat (1 tsp under each plant) or dilute it in a watering can at a ratio of 100ml to 10 litres of water.


Bokashi is a closed (anaerobic) food fermentation system developed in Japan. Bokashi bran is made from wheat flakes that are inoculated with EM (effective microorganisms) then air-dried. You can buy a bokashi bin from your local garden centre. This is usually a double-bucket system – the top bucket is for food scraps and the bottom one collects the juice. You add your kitchen scraps to the bucket and sprinkle the bran on top, then keep repeating until full.
As the pickling process (caused by the bran) occurs, a juice drips through holes in the top bucket into the bottom bucket. This liquid, which needs to be drained every 2-3 days to avoid it deteriorating, is full of microbes and nutrients which in turn are a powerful fertiliser for your plants. Once the bin is full, it is best to leave it for 2 weeks to ferment, then add the material to your soil by tipping it into a trench you've dug or by spreading it on top and covering it with a carbon material such as leaves, straw, paper or cardboard. Then plant your plants straight into it.
The juice is very strong and should never be put on your plants neat. The dilution ratio is 1-2 tsp to 5 litres of water. To combat pests and disease, this can be increased by 1ml at a time until plants have recovered. Undiluted juice can also be tipped down drains and sinks to add beneficial bacteria to your pipes and stop odours.
Over the past 15 years, I have done many experiments – small and large scale – using bokashi and have had outstanding results with growing food. The plants are much healthier, need less watering and the colour of the leaves is far more vibrant. I have used it on a large scale at restaurants and in turn created more usable soil, building up garden beds and diverting more than 19,000 litres of food waste away from landfill over a two-year period.
Remember, composting is fun, beneficial for your garden and, most of all, good for the planet. Happy composting!

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