Unsuitable Compost Ingredients
Learn which materials are unsuitable compost ingredients.
The following is a list of items that you should not use as composting ingredients. Some experts say you should not attempt to compost these materials in a domestic situation unless you are very experienced or are using a specialist system such as Bokashi. The rules apply either in a backyard composting situation or in, for example, a worm farm.
In some areas, mainly in the US, a permit has to be obtained to compost certain items, especially kitchen waste, or indeed to compost at all. On the other hand you will come across composters who maintain that as long as your pile reaches the correct temperatures, there is no reason why you should not go ahead.
Me? I would err on the side of caution every time and be very conservative when choosing compost ingredients – at least to begin with.
|Unsuitable Compost Ingredients – Avoid||Notes|
|meat and meat products||Meat products make unsuitable compost ingredients as they decompose very slowly. This can cause smells which will attract vermin and flies. The fat in meat products can choke your compost and halt the composting process.|
|fish||As for meat.|
|dairy including butter milk yoghurt cheese etc||Slow to break down with resultant rancid smells that attract flies and other nasties. Again fat is a major problem making dairy products unsuitable compost ingredients.|
|bones||Turns your pile into an all-night cafe for dogs cats and vermin. Don't do it!|
|fat or oils of any type||Will choke your pile.|
|glossy paper||Contains toxic chemicals that will compromise your finished black gold.|
|human waste||Contains harmful bacteria (pathogens) that can cause disease in humans and animals. Unsuitable!|
|pet waste||Contains harmful bacteria (pathogens) that can cause disease in humans and animals.|
|diseased plants||Your compost-heap needs to attain very high temperatures in order to kill harmful pathogens. If you are inexperienced the odds are these temperatures will not be reached and your compost will spread the infection in your garden. Dispose of these plants by burning or by taking to a commercial composting operation. They really are unsuitable compost ingredients.|
|pernicious weeds||A lovely term used by compost writers all over. I am stealing it because it is so descriptive. It seems to mean mainly plants that can develop growing shoots from the roots or that grow from rhizomes. Agapanthus is one that springs to mind although in many countries it would not be considered a weed.|
|any materials with chemical residue including herbicides and pesticides||Some say the composing process will neutralise the chemicals. Others say this is not the case. Better not to take the risk till more info is available.|
|cooked food||any fat will choke your compost and some advise that no cooked food is used. However others will say that bread and other flour-based foods like pasta and grains are fine to use in moderation. Best to experiment and make your own choices.|