I Often get asked the question about what you can and can’t put into your compost or worm farm. Strictly speaking the answer is that anything that was once living can be composted or put into the worm farm, however, in practical terms the answer is not as straight forward as this.  What is theoretically possible, such as composting meat scraps, can have unintended consequences such as attracting rats to your compost area. So, depending on your individual circumstance, here are my thoughts on the subject.

With human population on the rise at a very fast rate, many people’s attention is being drawn to the problem of landfill. Not only is filling up a lot of space very quickly, but as it does so,  the gas methane is emitted which is many times more potent than carbon dioxide as a greenhouse gas. This methane is sometimes recycled and used as a biogas fuel and that is a positive outcome in one sense. However, the quality of our Earth’s soil is going down because nutrients such as phosphorus are being taken out when we produce vegetables and if the waste goes to landfill those nutrients are lost to your soil. Add to that the fact that the world’s supply of phosphorus reserves (and other nutrients) are finite, many people are looking at what they can do about this on an individual level to turn waste into a resource and ensure that all those precious nutrients and carbon end up back in the soil where they belong. And as a further bonus this cuts by around 50% the amount of waste they send to landfill. A wonderful solution is to first recycle organic waste at home, either through a compost or worm farm, but what items can go into the compost and worm farm and what items have the potential to cause problems? To understand this a bit more, it can help to take a closer look at how it all works.

Worm farms use specially cultivated composting worms, such as red and/or tiger worms to process biodegradable waste. Composting  worms have their own microflora in their stomach and as they eat organic matter, it comes out the other end as finished compost, ready to use in the garden. With a worm farm, your organic waste goes in and worm castings and liquid organic fertiliser comes out. With a composting unit, micro-organisms such as bacteria and fungi are mostly responsible for the break down of any biodegradable waste put into the bin. Some composting units (such as the Tumbleweed Gedye Bin >>https://products.tumbleweed.com.au/collections/composting/products/new-150l-gedye-compost-bin are designed to be in contact with the soil, thus allowing any critters already existing in the earth, such as native worms to come up and feed on the decaying matter present within the bin. So, with all this in mind, it can help us to understand why certain items are more suited to a particular method, or not able to go into either for practical reasons

There is a lot of truth in the saying “what goes in must come out,” especially when dealing with the world of micro-organisms. There are certain biodegradable items that can contain potential pathogens (that are not visible to the human eye), that you might not want to introduce to your worm farm or compost (especially if you are using the products of these units for growing edible produce.) The examples of this include:

-Dog and Cat faeces which can carry pathogens that can affect humans (as well as re-infecting your pets)

– Animal meat and bones (which can attract vermin and in the case of bones, will take too long to break down)

– Dairy (including cheese and yogurt) unless mixed thoroughly through other organic materials such as vegetable scraps which dilutes the dairy products to a level where they are easily and quickly broken down without creating bad odours

In my opinion, it is best to keep these items out of your worm farm and compost if you are in the city or suburbia . So, if they are best left out of the compost or worm farm and you don’t want them to go to landfill, fear not, I have a suggestion if you have sufficient garden space! I have become an expert over the years at digging big holes for myself, but in this case, it’s totally appropriate for composting anything that doesn’t work in the compost bin or worm farm. This method is referred to as “trench composting,” where you dig a nice deep hole (It must be deep so that flies and vermin are not attracted to the site,) place the compostable items in and bury them.

Now that we have looked at what can’t go in, let’s look at the huge range of items that can be placed into the compost or worm farm:

– Any fruit or vegetable scraps. I’d like to make special mention here of citrus, pineapple and onion, which can in fact be placed in, despite what I often read in some gardening books and magazine articles. The tip is to mix them in thoroughly with other scraps so there is a balance, and if you are interested to learn more on this topic, I have some in depth articles available to read on my website.

– Egg shells

– Cardboard, paper, toilet rolls, paper towel, any paper or cardboard materials that do not have a glossy look. Some inks are plant based, so if they are, they are good to go in.

– Coffee grounds

– Tea leaves, or tea bags (if they don’t contain micro plastics – best to use tea leaves in your teapot if possible).

– Grass clippings, garden off cuts or raked up dried leaves. I recommend adding these to the compost rather than the worm farm, due to the large quantities they usually come in. Adding smaller quantities of these to the worm farm is fine though especially if you can chop the up in a mulcher for instance.

– Nut shells – again, crush them up if possible

– Hair from the brush (animal or human hair).

– Animal manures other than cats and dogs – Cow, sheep, donkey or horse manure is especially good

– Wool

– Any clothing made from organic material such as hemp, cotton, silk or wool. Just be sure to check labels.

It’s definitely worth mentioning that some items are more suitable to place in the compost, rather than the worm fam. If a worm farm becomes overloaded with more biodegradable items than the worms can eat in a good amount of time, it can cause bad odours or the presence of unwanted vinegar flies or fruit fly. If you find your worm farm can’t keep up with the amount of waste your household is producing, it might be time to also add a compost unit such as a Gedye bin. Also, if you find you have a lot of larger biodegradable items, compost units can generally fit more and also larger items, such as grass clippings, tree prunings and twigs. Some items can be placed in a blender, or cut up smaller so that the worms can process them more quickly and also, if you have a great excess of scraps in a particular week (such as around Christmas time) you could try freezing some of them to process later. One of the really important things to remember with both composting and worm farming is that balance is the key to greater success! If you add a wider variety of items into your unit and be sure to stick to a good ratio of both ‘greens’ (such as vegetable scraps) and ‘browns’ (such as dead leaves). I recommend about a 50:50 ratio but that it does not need to be exact, so, for every cup full of fruit and vegetable scraps, add in a cupful of carbon rich materials. This article link below has a lot more in depth information about what is considered a composting “green or brown” >>https://www.gardeningwithangus.com.au//managing-multi-level-worm-farms/

I hope this helps you to broaden your composting activities.

Happy gardening!