Composting. Sounds easy. Sounds good. So we all do it, right? Ha. I think composting is at risk of becoming a dying art in this day and age. People are too busy, they don’t have enough space, they can’t be bothered or they don’t know how. I’m still learning the art of composting myself. It works differently depending what kind of bin you use, what size it is and what climate you live in.
At the house in Christchurch we inherited one of those cheap black plastic cylinder bins that are so readily available. It never worked very well for me. Apparently you have to be very specific with your layers of compost matter as the narrow size of the bin means the conditions have to be just right for everything to decompose effectively, with less surface area and fewer organisms to do the job. Also, although I tried to water it a lot, the climate was so dry I could never get it to stay moist enough. It probably needed to be in a site with less sun in that sort of climate but there wasn’t anywhere else to put it. Then I moved on to the equally cheap but much better pallet compost bin, hastily assembled by The Husband, with a larger surface area. I filled it up with many things but didn’t get the chance to see the compost through to completion before we moved.
At the new house I have inherited a wooden two-bay compost bin. This is better than what I’ve had before, as two sections are better than one, and if you can have three that is the best! With two bins, one can hold your mature, currently usable compost while the other is for your in-progress compost. The problem with my compost bins was that one of the other residents who lives on the property had dumped loads of weeds on top of the compost bins. This mountain of invasive-looking grass weeds sat there ominously, on top of the covers of the compost bins, still alive and being completely useless. For a while I avoided dealing with this problem, while I busied myself hacking my way into the vege garden.

Finally, the day of reckoning came. It took me two days to have the motivation and energy to get rid of all the weeds onto the trailer. There were also mussel shells and whole, rotten eggs to remove, which I will not speak of. It was getting dark by the time I had finished. A couple of days later I went out there to empty our inside compost container and check out what was under the covers. The back bin revealed mature compost. Score! Although, it is a bit weedy, as weed seeds have obviously gotten in around the edges. The other bin revealed in-progress compost and a nasty surprise. Someone had put a whole plastic bag of meat in there, who knows when, and it was surrounded by hordes of maggots. Ewww!!! I can’t even comprehend why someone would do that. You’re not supposed to put meat in the compost, let alone plastic. It was so gross I ran and told The Husband. I couldn’t face dealing with it. The Husband rescued me and dealt with the offensive objects. Ah, it’s good to have a man around.
Now the compost bin is being used by us and our property-sharing neighbours. It just has a few weed problems around the edges that I need to deal with. This little story brings me to thinking about what not to put in a compost bin and why. I am not going to do an extensive run-down on how to compost, as there are many good websites out there for our reading pleasure. But I have found that the what not to put in section is a little light on items and reasons in some sources, so here’s the list I have collected.
What Not to Put in a Compost Bin
- Invasive plants (eg. dandelion roots, dock, oxalis, couch and kikuyu grass, ivy and convolvulus). Why? They can grow in the compost and spread through the garden.
- Plant material that is diseased. Why? Diseases can spread into the compost and subsequently through the garden.
- Plant material that has been sprayed with weed killer. Why? The presence of weed killer in the compost could affect plant growth.
- Sawdust or wood shavings from treated wood. Why? The chemicals, particularly arsenic, are a health risk to humans.
- Walnuts or material from walnut trees. Why? They contain a natural chemical called juglone that is toxic to some plants.
- Meat, fish or dairy products. Why? They attract flies and unwanted animals and are smelly.
- Oil or fat. Why? It attracts unwanted insects and animals, can unbalance the compost moisture level and can coat material, preventing it from breaking down.
- Cooked food. Why? It attracts bad bacteria and animals that are unwanted in the compost.
- Bread products. Why? They attract flies, maggots and unwanted animals.
- Human or domestic pet waste. Why? The potential for disease organisms is a health risk to humans.
- Large or thick woody stems. Why? They take too long to rot.
- Printed paper and foil (e.g. magazines, pamphlets, cards, wrapping paper, metallic paper and foil). Why? They may contain chemicals harmful to plants and good organisms and foils don’t break down readily.
- Anything non-biodegradable or toxic, things that aren’t obviously plant-, food-, paper- or hair-related (e.g. plastic). Why? They don’t break down and may contain chemicals harmful to plants and good organisms.
Citrus fruit should be composted in moderation so the compost doesn’t become too acidic for worms.