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These 8 things you should not put on the compost

Composting is an easy way to turn your kitchen and garden waste into something useful for your vegetable garden. But not all are equally suitable for composting for one reason or another . For example, some food waste produces an odor that can attract pests. And certain yard waste can slow or stop the decomposition process, which can be frustrating. Also, don’t put anything in the compost that could harm you or your plants later. Here’s what you definitely shouldn’t throw in your compost garbage can, along with a few household wastes you probably didn’t know were suitable for compost.

What should you NOT put in the compost?

Proper composting - This does not belong in the compost bin

While there are some wastes that are best added only in small quantities, the following items are completely unsuitable for the compost:

1. meat and fish scraps.

Do not put meat scraps and bones on the compost

The fishy stench of old seafood or the putrid smell of rotting meat, while repulsive to humans, act as magnets for skunks, raccoons, rats, flies and many other wild animals and even some neighborhood pets. So unless you want to provide a picnic for local wildlife, never add meat, fish or bones to your compost pile. Even if you have a closed compost bin, the smell can attract unwanted pests.

2. dairy products, fats and oils.

Dairy products, fats and oils not on the compost

Dairy products such as cheese, butter, milk, sour cream and yogurt, as well as fats and oils, should be avoided for the same reason: They attract unwanted visitors. So processed foods that contain a lot of dairy products or fat, as well as leftover feta salad, should not be put in the compost.

3. plants or wood treated with pesticides or preservatives.

painted, stained or varnished wood not compostable


Plants that have been treated with insecticides, fungicides or herbicides do not belong in the compost pile. Residues of chemicals used in the garden to kill insects and control plant diseases can inadvertently kill beneficial composting organisms. Residues of herbicides can affect plants in the garden after compost is added. The same is true for pressure-treated, painted, stained or varnished wood.

banana peels lemon only suitable for compost in small quantities

Oranges, lemons, grapefruits and exotics such as pineapples, avocados and bananas have mostly been treated with harmful sprays in the countries of origin. The toxins that collect in the future compost are very low after a good composting, but it is advisable to avoid large quantities of these wastes. In addition, the citric acid in the peels of oranges, tangerines, lemons and grapefruits is unpleasant to compost worms and other soil organisms. So, tropical and citrus fruits compost well, but care should be taken to get the proportions right. Cut the peels into pieces to help them decompose faster.

4. the foliage from the black walnut tree.

Do not put the leaves from the black walnut tree on the compost


Most untreated garden waste is a good addition to your compost pile, but there are exceptions. The leaves, twigs, fruit skins and especially the roots of the black walnut tree contain a natural substance called juglone that inhibits the growth of many plants and can even kill them. Certain plants appear to be more sensitive, including edible crops such as tomatoes, peppers and potatoes, and ornamentals such as azaleas, hydrangeas and the snowball (Viburnum) plant genus. Research has found that juglone will break down sufficiently with enough time and heat to lose its toxicity, but it’s better to leave the black walnut residue out than to deal with potential problems later.

what leaves to the compost

What foliage should not be put in the compost yet? Oak, beech as well as chestnut leaves rot only with difficulty and are not recommended for the compost. The foliage of plane trees, poplars and cherry laurel also causes difficulties in composting.

5. diseased or insect infested plants.

why not put tomato leaves on the compost

To kill insects and pathogens such as fungi and bacteria, a hot compost pile is required (one that reaches and maintains a temperature of 60°C to 70°C for at least several days). However, most home compost garbage cans and piles never reach such high temperatures, so it is possible for pests and diseases to survive in them.

Unfortunately, the nightshade family (Solanaceae), which includes potatoes, tomatoes, eggplants and peppers, are susceptible to all sorts of diseases. Tomatoes and potatoes, for example, are often attacked by blight (Phytophthora infestans). If diseased leaves are disposed of in the compost, the fungus can continue to multiply. There is nothing wrong with composting healthy tomato leaves or potato weeds.

6. weeds that have already formed seeds.

What weeds not to compost

If the weed has already formed seeds, it should not end up in the compost. As long as compost temperatures do not reach 70°C, the seeds can survive composting and germinate again when discharged into the soil. The No. 1 rule for weeds is: never let them go to seed! You can learn more about the different types of weeds in this article .

7. ash from charcoal

Ash from charcoal not on the compost

Although you can add ash from your wood-burning fireplace or hearth (in limited amounts) to your compost, you should leave out coal and charcoal ash. First, these materials contain a lot of sulfur, which can make the finished compost too acidic for most plants. Second, charcoal briquettes are often laced with chemicals that can harm plants.

8. dog or cat feces.

Cat droppings should not be put on the compost

Dog and cat feces do not belong in the compost pile because both cats and dogs can carry bacteria and parasites that cause disease in humans. Nematodes are the most common problem with dog feces. Cat feces and litter are even more concerning because they can contain the parasite that causes toxoplasmosis – a disease that is especially dangerous for pregnant women because it can cause severe damage to an unborn child.

Surprising things you can compost

Laundry dryer lint may be put on the compost

Now you know the scraps you shouldn’t throw in the compost, but there are many others you probably didn’t know were suitable for compost. However, only add the following items if they are free from the taboos above.

  • Hair and fur
  • Clothes dryer lint
  • Aquarium plants
  • Brewing waste (spent grains, spent hops)
  • Used paper napkins and paper towels
  • Old herbs and spices
  • Unpopped or burnt popcorn
  • Cardboard and paper plates (small pieces, uncoated)
  • Wooden chopsticks and toothpicks

Put food scraps in the compost garbage can