Last updated on October 23rd, 2023 at 08:50 pm
With your indoor or outdoor compost bin, you can create your own natural fertilizer. In this clever mix of green and brown waste, you will often find food waste as well as household waste. Tea bags without staples, coffee grounds, crumbled eggshells, fruit and vegetable peelings… The possibilities are numerous. However, if you think of your composter as a second garbage can, you could end up harming it. Added in the compost, some foods can indeed unbalance it, decompose badly, promote bad smells or invite pests. Find out which ones are forbidden in compost and which ones should be added in small quantities to keep it healthy.
1) Leftover meat or fish
Fish and meat scraps as well as cooked food require high temperatures for proper decomposition. This is a condition that our compost bin does not meet. Moreover, these foods can attract animals to your compost (dormice, rats, etc.). They can also promote bad odors. It is therefore recommended to add them in very small quantities. Be sure to cover them with 10 to 20 cm of humus to limit the risk of attracting undesirable animals.
2) Too many citrus peelings
In addition to being very thick (therefore difficult to break down), the peels of your lemons, oranges and other grapefruits have the disadvantage of being very acidic. Of course, nothing prevents you from adding small pieces from time to time. However, be aware that too much of them can unbalance the pH of your compost. Moreover, these fruits are unfortunately heavily treated with chemicals during the growing and harvesting process. They are therefore covered with bactericidal agents that are very harmful to the micro-organisms at work in your composting bin. It is therefore better to keep these precious peels to give a good smell to your household vinegar!
3) Waste from dairy products
Over time, dairy products can macerate and release foul odors. Leftover butter, milk and other cheese rinds can also choke your compost and attract all the pests around. For a healthy compost, it is better to avoid these foods or at least limit them as much as possible!
4) Seeded foods: beware in the compost!
Some foods such as tomatoes or pumpkins have seeds that can quickly germinate in the compost bin. So be careful if you decide to throw away foodstuffs that contain seeds to avoid unpleasant surprises!
5) Rhubarb leaves and garlic
Do you have any leaves left over after making rhubarb jam or pie? They are indeed toxic and therefore remain on our hands when we have finished our preparations. If there are many ways to recycle and use these leaves intelligently, adding them to the compost is definitely not one of them. Indeed, these wastes have a strong insecticidal power that may harm your compost. For the same reason, garlic should also be avoided in compost (or added in small quantities only).
6) Fats are a bad food for compost
Oils, mayonnaise and fats in general do not break down easily at low temperatures. Also, oil in compost can slow down the decomposition process by reducing air circulation. This is detrimental to the quality of the compost. Grease also tends to attract rodents. If you absolutely can’t take it to the dump, you can scatter it on your compost heap or on a soaked carbon support (paper or cardboard). However, do so in very small quantities.
7) Be careful with foods that are difficult to decompose in compost
Some foods should not be banned from the compost as such. However, you must take precautions before adding them, otherwise they will not be able to degrade properly. This is the case for dried fruit shells (nuts, peanuts, etc.) or seafood shells (oysters and mussels), which should be finely ground, just like cabbage cores.
Eggshells and potato peelings are great additions to your future homemade fertilizer, but cut them into small pieces to facilitate their decomposition. As for the corn cobs, don’t neglect the drying step before crumbling them. This will help to blend them more effectively. Finally, limit the use of avocado or pineapple skins, which are too hard, and add bread sparingly and well-crumbled so as not to suffocate the compost.
Remember that in addition to these foods, other elements should be banned from the compost!
This is particularly true of bioplastic bags, which are not very biodegradable. Plants that are diseased, full of parasites (aphids, etc.) or dead should also be strictly banned. They risk contaminating your compost, and therefore the rest of the garden at the time of spreading. This also concerns weeds that have gone to seed and will be spread all over your green spaces in no time. Finally, the residues of lawn mowing or plants treated with pesticides or herbicides should be limited to a maximum.