An easy and effective way to divert your food scraps from landfill and create your own nutrient-rich compost.
By sticking to a couple of rules, cold composting can be an easy and effective way to divert your food scraps from landfill and create your own nutrient-rich compost.
Cold composting (just like hot composting) relies on layering nitrogen-rich and carbon-rich materials to create the right conditions for composting.
One stark difference between cold and hot composting is that with cold composting you can build your pile over time as you collect your layers – whereas with hot composting you collect all of your materials and then make your hot compost pile in one go.
Knowing which materials fall into which group is the first step. The nitrogen (“green”) camp includes manure, fresh grass clippings, food scraps, coffee grounds and seaweed. The carbon (“brown”) camp includes drier, woodier materials like straw, dried leaves, untreated sawdust, wood chips, old dry grass clippings and shredded cardboard.
The key to cold (and hot) composting is that whenever you put in some nitrogen (eg food scraps and/or fresh grass clippings), you need to add a similar amount of carbon (eg straw and/or wood chips). Each layer should be 5-10 cm deep.
The second thing that the heap needs to break down is moisture. Water each layer as you go, before covering the heap until the next time you add to it. You can use old carpet, black plastic or an old wool sack. When the heap is a good size (approx one metre high), cover it up for good and leave it to mature. Check the moisture levels occasionally, especially around the edges. When you take a handful of your compost and squeeze it in your hand a few drops of water should escape just like it would when you squeeze a wet dishcloth.
To speed up the process, aerate the heap or turn the pile, mixing the ingredients up thoroughly. The more you turn it, the quicker you will make compost. The whole process will take 12 months or more (less with regular turning). This is longer than with a hot compost (when you gather large piles of materials and make the heap all at once), but the advantage is that you can build your compost heap gradually over weeks or months as the materials come to hand.
EXAMPLE 1
You add a bucket of food scraps (“green”) in to the heap every second day. Fork in an equal amount of straw (“brown”) at the same time. A sprinkle of water, cover the heap and you’re done.
EXAMPLE 2
You mow the lawn producing three to ten catcher’s full of clippings. Rather than dumping the whole lot onto the heap, alternate a 5-10 cm layer of fresh grass (“green”) with a 5-10 cm layer of leaves (“brown”) or straw (“brown”). Remember green, brown, green, brown, green, brown. Don’t forget to sprinkle some water on every layer as you go.
EXAMPLE 3
You buy four bags of manure (“green”) from the side of the road. Save the bags of manure to increase the variety of nitrogen-rich materials you’re adding in. Especially good when you’ve tidied up a whole load of dry material (“brown”) in the garden (eg chopped up prunings).
Don’t see the question and answer to what you’re looking for? Keep an eye out for one of our seasonal workshops.
Whether you are just starting on your composting journey or you want to improve your current composting set up, our Composting Guides will give you the knowledge to feel confident to take your composting to the next level and divert organic waste from landfill.
Kitchen scraps and garden waste make up a third of household waste. Putting them in the landfill can be harmful as organic waste releases methane, a climate change gas. The Dr Compost project helps people in the Queenstown Lakes district to reduce their waste and feed their soil by composting at home. Dr Compost is funded by Queenstown Lakes District Council and delivered by Wastebusters.
Sign up for our Wastebusters’ newsletters to stay up to date with Dr Compost’s news and events, best tips and tricks and secrets on how to compost and garden like a pro in our district.
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This year our amazing Wastebusters whānau has been busy keeping everything we can out of landfill and supporting resourcefulness in our community while also working on bringing our dream of Wastebusters 2.0 into reality.
We were humbled and absolutely stoked to take home the Wānaka Chamber of Commerce Business Awards Supreme Business Award, along with the Community Contribution and Business Sustainability awards. This success was a powerful recognition of the dedicated mahi of our entire team, giving us huge confidence for the ambitious journey ahead.
We welcomed Aviette Musin on a fixed-term contract as our new Programme Manager for Wastebusters 2.0. Her expertise provided the dedicated, focused capacity needed to accelerate progress on this strategic goal.
Funding was secured through Queenstown Lakes Community Composting Project for the Compost Collect pilot, a joint venture with our neighbours Wānaka Greenwaste that will turn commercial food scraps into valuable compost, launching in 2026. We also intensified our focus on Construction and Demolition (C&D) materials, trialling diversion methodology and securing initial partnerships to divert waste from landfill. With our current site so space-constrained, we are extremely limited in the C&D materials which can be accepted for reuse, but this work will lay the groundwork for future diversion on a bigger site.
We made a compelling case to the Council for the necessary land expansion for Wastebusters 2.0 and prepared for the MfE Waste Minimisation Fund application process to support our expansion plans.
A continued focus for us this year has been on strengthening the Wastebusters whānau and ensuring we are equipped not just for the daily challenges, but for future growth. We continued to be a Living Wage employer, reflecting our commitment to the well-being and value of our staff. Feedback from the team via staff survey results highlighted strong morale and resilience within our workplace culture with 89% saying they enjoy working at Wastebusters and 93% feeling cared for by their manager.
The district’s rapid growth brings challenges as well as opportunities, particularly the Ballantyne Road/Riverbank Road roadworks which demanded flexibility and good humour from our team and customers throughout 2024. Despite the road cones, ongoing community support ensured our Reuse Shop continued to be a first choice destination for both locals and visitors. Improved donation flows and adding new changing rooms has made the shop operation smoother and more efficient for everyone.
Wastebusters’ partnership with events continues to go from strength to strength: including the trial of a food scraps collection from vendors. And our Recycle team did the huge job of relabeling all our events recycling bins to align with national recycling colours, making it easier for event-goers to know what to do. Wastebusters recycling trucks continue to be a much-loved presence in town servicing our 408 business customers, with the team doing a great job of keeping our aging fleet serviceable, in line with our kaupapa of keeping resources in use for as long as possible.
Our Reduce team has continued to deliver exceptional impact, with more than 11,000 people engaged in person through our education and engagement in the community. The Resourceful Communities programme inspires our community to take action and builds the knowledge and know how to engage in areas like repair, low waste living and textile waste diversion. It is proudly supported by QLDC’s zero waste district’s programme which recognises the impact of community connection for zero waste action.
We were stoked to join Environment Hubs Aotearoa, and we look forward to collaborating with this network and amplifying our collective impact on environmental action and resourcefulness across Aotearoa.
We worked with an impact consultant to implement an evaluation framework and behaviour change model to better plan, deliver and measure our impact, and have begun rolling out our learnings across all our programmes.
It was a busy year in advocacy, starting with participation in QLDC’s Waste Management and Minimisation Plan process. We appreciated QLDC’s approach in bringing Wastebusters and other stakeholders in early in the process, which has resulted in a constructive plan for the next six years. Wastebusters has also made submissions on national and local level, including The Right to Repair Bill, the Container Return Scheme and the publicly notified resource consent for McDonald’s in Wānaka.
Ultimately, this year has been about delivering impact while building the foundations for a much larger and even more impactful operation, securing Wastebusters’ future for our community. The heart of our work remains resource recovery and community engagement, and we enter the next 25 years of zero waste leadership with great confidence, welcome community support and an unwavering focus.
Gina Dempster
General Manager
November 2025
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