Composting in New Zealand

Composting is the engine room of a productive backyard. It turns garden waste and kitchen scraps into free soil food, keeps organic matter out of landfill, and closes the loop so what your garden grows eventually feeds it again. Almost every section has room for some form of composting.

There is no single right method. Hot compost is fast but needs feeding and turning, cold compost is slow but almost no work, and bokashi ferments scraps that ordinary compost cannot handle. Many New Zealand councils now also collect food scraps at the kerb, so it helps to know how home composting fits alongside that.

Hot composting

Hot composting builds a large pile all at once and lets it heat up as microbes break it down. A good hot heap can reach temperatures that kill weed seeds and many pathogens, and it can produce finished compost in a couple of months.

The trick is balance. Mix roughly equal parts of green material (grass clippings, kitchen scraps, fresh weeds) with brown material (dry leaves, cardboard, straw), keep it as damp as a wrung-out sponge, and turn it every week or two to feed it air. If it is built well and turned, it rewards you quickly.

Cold composting

Cold composting is the relaxed option. You simply add material to a bin or heap as it comes and let nature take its time. It does not heat up much, so it will not kill weed seeds, but it asks almost nothing of you.

This suits people who generate scraps and garden waste in dribs and drabs. The pile breaks down over many months to a year, and you take finished compost from the bottom while still adding to the top. It is the easiest way to start.

Bokashi

Bokashi is a sealed bucket method that ferments food scraps rather than rotting them. Because it pickles the waste with an inoculated bran, it handles things normal compost and worm farms cannot, including cooked food, bread, cheese, meat, fish and small bones.

Once a bucket is full and fermented you bury the contents in the garden or add them to a compost heap, where they break down quickly into the soil. Bokashi suits small sections and cold or wet regions, and it keeps pest-attracting scraps sealed away while they ferment.

It is a good companion to a worm farm: the scraps worms dislike, such as onion, citrus, meat and dairy, can go through bokashi instead.

Council food scrap rules

Food scraps make up a large share of what New Zealand households send to landfill, where they release methane. To cut that, a number of councils now run kerbside food scrap collections with a kitchen caddy and a bin, and others offer green or organics bins for garden waste.

Home composting is still the better option where you can do it, because it keeps the nutrients on your own section. Check your local council to see what collection or green waste service is offered in your area, then compost what you can at home and put the rest in the kerbside system.