Strictly speaking, anything that once lived can be composted. This list includes anything from plants, food waste and dead animals to excrement and anything made from natural fibres. However, time, space, smell, disease and unwelcome pests are all factors to consider when determining what to compost at home (for non-domestic composting there is also legislation to abide by, particularly the animal by-products regulations which came about following the foot-and-mouth crisis).
Compost needs warmth, air, water and raw materials. These raw materials fall into two groups: greens and browns. Greens are the wet stuff like vegetable peelings that are nitrogen-rich and quick to rot, and browns are the dry, carbon-rich things like toilet rolls and autumn leaves that are slower to rot but they help provide air pockets so the air can circulate through your compost. A balance between the two is essential for good compost. Although some schools of thought recommend ‘layering’ greens and browns, Garden Organic teach that this is not necessary so long as equal amounts of both are going into the bin, and suggest mixing drier, tougher ingredients with greens before adding them to the bin. This can be a challenge depending on your set-up – if you have a big garden and collect lots of garden waste then you might not need to worry. But, I find I have to pair my kitchen waste with things like toilet rolls, egg boxes, and other paper recyclables.
How can you tell if you’re getting the balance right?
‘Greens’ (nitrogen-rich ingredients)
- Young weeds
- Nettles (not roots)
- Comfrey leaves – compost separately to make a comfrey solution, a natural plant food (a fellow Master Composter uses an old bokashi bin for this purpose)
- Urine (ideally diluted 20:1)!
- Uncooked fruit and vegetable peelings
- Tea bags, leaves and coffee grounds (including coffee filters – make sure you choose biodegradable teabags and coffee filters)
- Soft green prunings
- Animal manure from herbivores (e.g. cows and horses)
‘Browns’ (carbon-rich ingredients)
- Cardboard (e.g. cereal packets, toilet roll tubes and egg boxes)
- Waste paper and junk mail, including shredded confidential waste (watch out for any plastic packaging)
- Paper towels & bags
- Bedding (hay, straw, shredded paper, wood shavings) from vegetarian pets (e.g. rabbits and guinea pigs)
- Tough hedge clippings
- Woody prunings
- Old bedding plants
- Egg shells (ideally crushed)
- Natural fibres (e.g. wool and cotton)
- Hair (avoid if it has been chemically treated with hair dye)
- Grass cuttings – can be composted in moderation (mixed with dry material to create air pockets) but far better to compost separately, leave on the grass for the worms, or use as a mulch
- Autumn leaves – can also be composted in moderation but far better to compost separately to make leaf mold
- Meat, fish, dairy products or cooked food (alternative methods are available – e.g. bokashi, green cone, trench)
- Coal & coke ash
- Cat litter and dog faeces (alternative methods are available, likewise composting toilets for human faeces)
- Disposable nappies (even biodegradable nappies may take several years to fully decompose and unless a vegetarian diet is being followed then soiled nappies should be disposed of separately)
- Do not compost anything that has been chemically treated – e.g. wood, carpets, dyed hair
Just because something is considered a caution does not mean it will not compost. As I stated at the beginning, anything that lived can theoretically be composted, but we can’t just pile it all on a compost heap without considering the environment around us. Some things, like large woody prunings and Christmas trees should be shredded before being added to a heap (it is also noteworthy that some Christmas trees are sprayed with fire retardant and you do not want those chemicals mixing in with your nutritious compost) but the quantity may still be too much for the domestic compost. Industrial composting (where council green waste collections end up) are therefore more suitable for large garden waste and things like poisonous plants and weeds which need higher heats to ensure they will not be harmful to the soil and plants. Food waste has the risk of attracting pests, and spreading disease. Likewise, the excrement of non-vegetarian animals. However, there are ways of composting these things in a domestic environment. My next post will look at conventional compost bins. Following that I will explore the more non-conventional options.
The above photo was taken on my training weekend (I’m the second one in with glasses). We had to use some of the resources available to us to set up a stall to show people about composting. I am running my first composting workshop on Saturday. If anyone lives locally (Loughborough, UK), then please check out the details here and book a place!