Compost Troubleshooting
Compost problems almost always come back to one of three things: the balance of greens and browns, moisture, or air. Read what the heap is doing and the fix is usually quick.
Smelly or slimy
A heap that smells sour or like ammonia and turns to slime has too much green material and too little air. Mix in plenty of browns, dry leaves, straw, shredded cardboard, and turn it to get oxygen through. The smell clears within days once the balance and airflow come right. A thick mat of fresh grass clippings is the usual New Zealand culprit.
Dry and nothing happening
If the heap is dry and sitting there unchanged, it is either too dry, too full of browns, or too small to get going. Add green material and water it to the dampness of a wrung-out sponge, and build it up to a decent volume, since a tiny heap struggles to keep itself active. Turning reintroduces moisture and microbes through the pile.
- Smelly and slimy: too wet and airless, add browns and turn
- Dry and inactive: add greens and water, build up the volume
- Rats or flies: keep food scraps buried, leave meat and dairy out, secure the bin
- Slow but otherwise fine: chop material smaller and turn more often
Pests and slow heaps
Rats and flies mean exposed food scraps, so bury kitchen waste in the centre, keep meat and dairy out entirely, and use a bin with a lid and a base if rats are a problem. A heap that breaks down slowly but smells fine is usually just cold or coarse, so chop material smaller, mix greens and browns more thoroughly, and turn it to speed things up. Through a cold New Zealand winter every heap slows down, which is normal and picks up again as it warms.
Frequently Asked Questions
Why does my compost smell bad?
Too much green material and not enough air. The fix is to mix in browns like dry leaves, straw or cardboard and turn the heap to add oxygen. The smell usually clears within a few days.
Why is my compost not breaking down?
Usually it is too dry, too coarse, too small, or just cold. Add greens and water to dampen it, chop material smaller, build the heap up to a good volume, and turn it. Heaps also naturally slow over a cold winter.
How do I keep rats out of my compost?
Bury food scraps in the centre of the heap, keep meat, dairy and fat out entirely, and use a bin with a secure lid and a base. Rats are drawn to exposed and inappropriate food, so removing that removes the attraction.