What Can Go Into Your Compost Heap (And What Can't)

Composting is one of the most important ways to reduce food waste and live in a more sustainable way. Whether you have a garden or not, you can compost food scraps and keep them from landfills. Many people get a bit confused about what they can compost and what they can't. So here is a brief guide to help you get it right.

First of all, it is important to mention that how you choose to compost will determine to a degree what you can and cannot add to the system. But for all forms of composting, certain rules remain the same. It really is very simple.

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What Can Always Be Composted

Generally speaking, we separate everything that can go into a composting system into two categories: green materials (which are rich in nitrogen) and carbon-rich materials (which are high in carbon). In order to make good compost, you need to make sure you have the right mix, with both types of materials.

When it comes to green materials, no matter which composting method you have chosen, you can always compost:

• Fruit and vegetable scraps (except, in limited cases, excessive amounts of very acidic material like citrus peels, and things like avocado pits which take too long to break down).
• Cooked leftovers from vegan meals.
• The leaves of deciduous trees, shrubs and other plants. (Including grass clippings as long as you don't overwhelm smaller systems or add too much at one time.)
• Tea leaves/ coffee grounds (as long as you don't add too much at one time to smaller systems).
• The feces of smaller, herbivorous pets (rabbits, guinea pigs, gerbils, hamsters, etc..)
• Chicken manure (unless the composting system is very small and would be overwhelmed).
• Hair (your own or your pets'). (Though longer hair should be chopped up small as it will take a while to break down. And you should avoid it if your hair has been treated or dyed with chemical products.

When it comes to brown materials, again, no matter which composting method you have chosen, you can always compost:

• Untreated paper and brown cardboard.
• Sawdust/ smaller wood shavings (such as pet bedding, for example).
• Straw/ dried bracken.
• Deadfall leaves. (If your composting system is not too small to accommodate them.)

What Can Sometimes Be Composted

There is a further category of things that can sometimes be composted, but will require certain specific methods or setups. These include:

• Meat and dairy products. (These can be fermented in a bokashi bucket and can then be safely added to most composting systems).
• Bread and baked goods. (These can be added to most composting systems when broken up without any issues. However, if you have an uncovered outside heap, they may attract rodents or other scavengers.)
• Organic cotton/ other entirely natural materials like hemp, linen, silk, wool, etc... (Though fabrics will take longer to break down than many other materials, and so are best chopped up small and added to a longer-term composting heap or bin, or buried in the soil in your garden.)
• Larger pieces of wood or bamboo. (These will decompose, but again, will take longer to do so. You should not add anything that will take too long to break down in a small indoor system. Ideally, these should be broken up or chipped before composting.)
• Human waste (and the waste of meat-eating pets like dogs and cats). (These should only be dealt with in very carefully managed hot composting/ humanure systems, and should never just be added to a general purpose composting system, since pathogens could be dangerous. Expert knowledge is required to manage such waste in a safe way.)

What Can Never Be Composted

• Plastic-coated paper/ cardboard. (The plastic will not biodegrade).
• Teabags which contain plastic sealant. (Always check to make sure your tea/coffee bags are plastic free.)
• Synthetic fabrics (or fabrics with harmful dyes or treatments).
• Lint from a washer/drier (unless you never wash synthetics and only own entirely eco-friendly natural material clothes).
• The contents of your vacuum cleaner (if you have any synthetic carpets or rugs, or wear synthetic clothes, this will contain micro-plastic particles).

I hope this has made things a little clearer. Once you start composting, you will discover that the process is largely very simple and straightforward. But there are a few things to learn. Think about mixing brown and green materials in layers, make sure the compost is not too warm or cold, wet or dry, make sure it remains aerated, and you should not go too far wrong.