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What should not be in the compost: these wastes can slow down or even stop the decomposition process

Composting is an easy way to turn kitchen and garden waste into something useful for the garden. But not all are equally suitable for it. Some food waste creates an odor that can attract pests, and some garden waste can slow or stop the decomposition process, which can be very unpleasant. You don’t want to add anything that could harm you or your plants when you use finished compost in your garden, do you? Find out what can’t go in your compost and what household waste you probably don’t know you can compost in this article.

What NOT to put in the compost – meat and fish scraps

What must not be put on the compost - Meat and fish waste

The stench of old seafood or the putrid smell of rotting meat is certainly unpleasant. But those same repulsive odors are magnets for raccoons, rats, flies and many other wild animals, including some neighborhood pets. So never add meat, fish or bones to your compost pile. Even if you have a closed compost garbage can, the smell can attract pests to picnic there.

Dairy products, fats and oils should not be thrown in your compost

Dairy products, fats and oils in the compost garbage can attract rats and flies

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. Processed foods that contain a lot of dairy or fat should also be left out.

Plants & wood that have been treated with chemicals.

What should not be put on the compost - Some waste can stop the decomposition process

Never add plants to your compost that have been treated with insecticides, fungicides or herbicides. Residues from chemicals used in the garden to kill insects and control plant diseases can inadvertently kill beneficial organisms in the compost. Residues of herbicides can affect plants once compost is added. The same is true for wood that has been pressure treated, painted, stained or varnished.

Plants that are diseased or infested with pests.

To kill insects and pathogens such as fungi and bacteria, a hot compost pile (which reaches and maintains a temperature of 60 to 63 °C for at least several days) is required. Unfortunately, most home compost garbage cans and piles never reach such high temperatures, allowing pests and diseases to survive in them.

What should not be in the compost – weeds that have seeded: The same goes for weeds that have developed seeds, which can generally survive as long as compost temperatures do not reach 63°C. There is no point in seeding weeds for next year while you are spreading your finished compost.

Dog and cat feces do not belong in the compost pile

Dog and cat feces can become hazardous waste


Dog and cat feces can turn the final product into hazardous waste because both cats and dogs can carry bacteria and parasites that cause disease in humans. Roundworms are the most common problem with dog feces. Cat feces and litter are even more concerning because they can carry the toxoplasmosis pathogen, a disease that is especially dangerous for pregnant women because it can severely harm the unborn child.

What not to put in the compost – black walnut tree debris

Black walnut trees contain juglone, which inhibits the growth of many plants

Most untreated garden and yard waste is a good addition to your compost pile, but there are exceptions. Black walnut tree leaves, twigs and especially roots 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 plants such as tomatoes, peppers and potatoes, and ornamentals such as azaleas, snowball (viburnum) and hydrangeas. Research has shown that juglone will break down over time and with sufficient heat to the point where it loses its toxicity, but it is better to leave black walnut residue out in the first place.

Coal ash should be avoided

Coal ash does not belong on the compost heap


Ash on compost – although you can add ash from a wood-burning fireplace or hearth (in limited amounts), you should not add coal ash. First, these materials contain a lot of sulfur, which can make your finished compost too acidic for most plants. Second, charcoal briquettes are often laced with chemicals that can harm plants.

What mistakes should every gardener avoid when composting? You can read about it here !

These compostable products will amaze you

Composting for beginners - what should and should not be composted

Now that you know what not to do, here are a few tips. There are many waste products that you may not have thought of, but that you can safely add to your compost garbage can. However, only add the following items if they are free of the above prohibitions.

  • Hair and fur
  • Dryer lint
  • Aquarium plants
  • Home brewery waste (spent hops and malt)
  • Used paper napkins and paper towels
  • Old herbs and spices
  • Unpopped or burnt popcorn
  • Cardboard and paper plates (small pieces, not coated)
  • Wooden chopsticks and toothpicks

How can you speed up the composting process? You can find out here !

Summary – Composting for beginners

What can go in the compost:

  • Animal manure from herbivores
  • Brown paper products (cardboard rolls, cereal boxes, brown paper bags)
  • Paper towels, handkerchiefs
  • Coffee grounds and filters
  • Cotton, wool
  • Vacuum cleaner lint and dryer lint from natural materials
  • Crushed eggshells
  • grass clippings, garden waste
  • hair, fur
  • hay, straw
  • Houseplants
  • Leaves
  • Nut shells
  • Shredded newspaper
  • Wood shavings, sawdust, toothpicks, burnt matches
  • Fruit and vegetable peels
  • Old vegetables
  • Stale bread
  • Corn husks
  • Non-glossy advertising mail or catalogs (shredded)
  • Pine cones
  • Paper egg cartons
  • Tea leaves/used tea
  • Cooked rice/pasta
  • Wine corks
  • Simple paper documents

Tip. Some materials, such as onion scraps, citrus peels, stale bread and eggshells, are best added to the compost in small quantities only.

What NOT to put in the compost:

  • Meat products and fishery products.
  • Dairy products
  • Treated wood/sawdust
  • Acidic foods
  • Oils or greasy foods
  • Pet waste
  • Human waste
  • Weeds that have turned to seed
  • Leftover onions and garlic
  • Plastic
  • Coated cardboard
  • Cellophane
  • Poisonous plants
  • Diseased plants
  • Plants treated with pesticides
  • Coal ash
  • Products for feminine hygiene
  • Diapers
  • Synthetic fabric
  • Leather goods
  • Glossy paper
  • Wrapping paper
  • Glass
  • Black walnut products