The Greens, the Browns, and the No-Nos

So what should you add to your home compost pile? Indeed, there are ‘greens’ and ‘browns’ that are essential to making your compost pile work. A 50/50 mix of ‘greens’ and ‘browns’ is a perfect recipe for good compost. Confused? Fret not, simply read on.

(Note: Some information has been taken from www.recyclenow.com)

An example of 'browns' - fallen leaves

What are ‘browns’?

‘Browns’ are essentially carbon materials that soak up (or balance) moisture in your compost. They prevent your compost pile from getting too wet, and the more bulky-sized ‘browns’ also help to create air spaces between food scraps to facilitate aerobic (oxygenated) composting. This essentially prevents your compost pile from bad odours, and gives microorganisms the necessary oxygen to work.

List of ‘browns’ you can use – feel free to share your ideas too!

• Cardboard boxes
• Cereal/Tissue boxes
• Cards (e.g. greeting cards)
• Coffee filter paper
• Corn cobs – These may take a long time to compost so may have to go through the process several times. Breaking them up will speed up the process (e.g. chopping/smashing them up).
• Cotton towels – Cotton is a natural material which is compostable. Cut towels into small pieces and mix with an equal amount of green materials
• Cotton wool
• Egg boxes – cardboard, not plastic
• Fallen leaves and twigs
• Floor sweepings (use discretion)
• Hair – Very slow to compost but adds useful plant nutrients.
• Nail clippings
• Natural corks – Although they will take an incredibly long time to break down, natural cork is a valuable addition to the composting process
• Newspapers
• Nuts – Anything that was once alive can be composted although it will take a long time for nuts to rot down.
• Paper – non-glossy ones as they take longer to break down. Remember to scrunch up the paper before adding into the bin to trap more air spaces! Waste paper can also include junk mail, shredded non-glossy office paper, old bank statements and credit card bills etc.
• Paper bags – To keep the air circulating in your bin, scrunch up your paper bags before adding them.
• Sawdust
• Silk clothing (shredded)
• Teabags
• Tissue paper (unsoiled!)
• Toilet paper rolls
• Twigs, branches, bark
• Used kitchen paper / paper napkins – A good source of carbon. Scrunch up if possible. Also, the cardboard centres of kitchen and toilet rolls are excellent compost ingredients because they help keep air in the bin.
• Vacuum cleaner contents – If the contents of your vacuum cleaner consist of household dust, it is safe to add to your compost bin. The dust may have a drying effect on your bin so make sure you combine with green materials to counteract this.
• Wood shavings and sawdust – Avoid chemically treated ones, such as kiln-dried!
• Wool clothing (torn up)

An example of 'greens' - raw vegetable and fruit scraps

What about ‘greens’? They are quick to rot, and they give important nitrogen and moisture for your compost pile.

‘Greens’ you can use:

• Coffee grounds - great as a compost starter as they heat up the compost pile very quickly!
• Discarded RAW vegetable and fruit wastes (e.g. discarded vegetable parts, fruit peelings, apple cores, banana skin, citrus fruit peels, fruit pulp, fruit seeds etc)
• Egg shells – Rich in calcium. Eggshells are good for adding minerals to your compost and are often still visible in well-rotted compost. Eggshells do not decompose in the bin but are broken down into tiny pieces. Crushing them first will help.
• Grass cutting
• House plants, old flowers – cut them up to smaller pieces first for quicker decomposition.
• Human urine! - This is a wonderful activator (did I mention free-of-charge?) to kick-start the composting process and just as effective as the ones you can buy from the garden centres. You can add it to your compost bin diluted to one part urine to 20 parts water. Be careful not to overdo it as it will make your compost too moist.
• Poisonous plants – Plants that are poisonous to eat will not poison a compost bin or plants that are fed with that compost.
• Salad leaves
• Soft green prunings
• Tea bags and tea leaves
• Uncooked vegetable scraps (e.g. carrot peels, carrot tops, vegetable pulp etc)

***The No-Nos (stuff you should NOT add into your compost pile at all)

• Aluminum foil – not of living origin so will not compost
• Animal/pet litter
• Bones – these attract vermin
• Cigarette ends - not of living origin so will not compost
• Charcoal ashes – harmful to compost microorganisms
• Cling film – not of living origin so they will not compost
• Coal ash – This is not suitable for composting as it may contain impurities.
• Cooked vegetables / cooked food (e.g. rice) – attracts pests and gives off bad odour
• Dairy products – Do not compost milk or any other dairy products as they can attract vermin. Nevertheless, there are alternative methods of recycling these which are not available in this home compost system.
• Diseased plants
• Disposable nappies – Even if nappies are biodegradeable they could be a health risk in a compost bin so should not be put in.
• Drink cartons – The waterproof lining is not of living origin so will not compost
• Bread – will attract vermin and pests
• Cat or dog litter – Toxocara and toxoplasma are dangerous diseases that can be found in used pet litter and can be passed on to humans. Some brands of litter say that they can be composted, and technically they can, but for health and safety reasons, this is not recommended.
• Fish – attracts pests
• Glossy paper – takes a longer time to break down and may harm microorganisms in the compost (e.g. shiny magazines)
• Laminated paper/card – the laminated plastic will not compost
• Meat – attracts pests
• Olive oil - In a small domestic bin, the oil will considerably impede the composting process because it will displace air and water. It could also attract vermin and pests.
• Oils or fats
• Perennial weeds or weeds with seed heads
• Pesticide-treated/poisonous plant materials – they are harmful to compost microorganisms and might contaminate the compost
• Human and pet faeces – they may carry diseases and smells, attracting vermin.
• Pet food – attracts vermin and pests
• Plastics, glass, metal - these will not break down at all
• Soiled tissues – Although it is beneficial to add paper to the compost mix, soiled tissues should be avoided as composting will not reliably destroy germs and pathogens.

The lists above will be updated from time to time with more items. To search for specific items, Windows users can press the ‘Ctrl’ key and ‘f’ key together to do a simple word search. Similarly, Mac users can press the ‘apple’ key and ‘f’ key together.

Other useful points to note (taken from National Parks Singapore) -

• Whenever you add more material to the pile, remember to add water to the mixture until it is moist to touch, but not dripping wet.
• Ensure that the pile is neither too wet nor too dry. If it is too wet, add more “browns”; if it is too dry, add more water.
• The compost mixture will heat up due to aerobic activity taking place. It is essential to let the temperature in the pile reach 70°C, as the heat will eliminate harmful bacteria in the mixture. (You may purchase a compost thermometer for this purpose.)
• The finished product should be dark brown, with a soft, crumbly texture. The whole process takes between 3-6 months, depending on the materials used.
• Ensure there is a mix of soft and hard materials, as the latter can create spaces in the mix, improving air circulation in the pile.
• The smaller the materials, the faster the decomposition process. Large branches can be chopped into smaller ones, while paper can be shredded before being added to the pile.
• Hard carbon containing materials such as wood shavings and sawdust take a long time to decompose. You should add only small amounts of these if you would like to get the finished product more quickly.