From Banana Peels to Branches: Mastering the Art of Composting

August 19, 2023 in environment, Sustainability

Article summary and Key takeaways: Composting is a natural process that breaks down organic materials into nutrient-rich soil. To create an effective compost heap, a proper balance of carbon-rich “browns” and nitrogen-rich “greens” is necessary, along with adequate moisture levels and regular turning of the pile. Ideal materials for composting include vegetable and fruit scraps, coffee grounds, eggshells, grass clippings, leaves, and shredded paper. Other materials that can be composted include cardboard, straw, wood chips, manure (from herbivores only), seaweed, and plant trimmings. However, there are certain materials that should never be put in a compost heap, such as meat and fish, dairy products, oils and fats, coal or charcoal ash, plastic or synthetic materials, and yard waste treated with herbicides or pesticides. Unconventional items that can be composted successfully include hair and nail clippings, old cotton clothing and towels, paper towels and napkins, wine corks, coffee filters, and vacuum cleaner dust. Some vegetables, like onion and garlic peels, potato peels, citrus peels, and tomato plants and leaves, are not recommended for composting but can still be composted if properly managed. Reasons not to compost may include lack of space or resources, concerns about odor or pests, or physical limitations or health conditions. Branches can be composted but should be chopped into smaller pieces and mixed with other compostable materials. Responsible waste management is important for a sustainable future, and composting plays a significant role in achieving that goal.

Things That You Should Never Put in a Compost Heap

Composting is a natural process that allows organic materials to break down into nutrient-rich soil, which can be used to improve the health of gardens and plants. Composting has numerous environmental benefits, including reducing waste sent to landfills and reducing the need for chemical fertilizers. However, it’s important to know what not to put in a compost heap to ensure its effectiveness and avoid potential issues.

Understanding the Basics of Composting

Before delving into the things that should never be put in a compost heap, it’s essential to understand the basics of composting. Composting is the decomposition of organic matter through the action of bacteria, fungi, and other microorganisms. These organisms break down organic materials like food scraps, yard waste, and leaves, turning them into a dark, crumbly substance known as compost.

To create an effective compost heap, certain factors must be considered. These include a proper balance of carbon-rich “browns” (such as leaves and shredded paper) and nitrogen-rich “greens” (such as grass clippings and kitchen scraps), adequate moisture levels, and regular turning of the compost pile to promote aeration.

Best Things to Compost

Before exploring the items that should never be put in a compost heap, let’s first focus on the materials that are ideal for composting. Some organic materials that are beneficial for composting include:

  • Vegetable and fruit scraps
  • Coffee grounds and tea leaves
  • Eggshells
  • Grass clippings
  • Leaves
  • Shredded paper

These materials provide essential nutrients, introduce beneficial microorganisms, and help maintain the necessary moisture levels for successful composting. To maximize the composting process with these materials, it’s important to chop or shred larger items into smaller pieces, as this speeds up decomposition.

What to Compost List

In addition to the above-mentioned materials, there are several other organic materials that can be composted. These include:

  • Cardboard
  • Straw and hay
  • Wood chips
  • Manure (from herbivores only)
  • Seaweed
  • Plant trimmings

These materials provide a range of nutrients and help maintain a balanced compost pile. It’s worth noting that different types of compost bins may have specific requirements, so it’s important to research the best composting methods for your specific setup.

Things That Should Never Be Put in a Compost Heap

While composting is a versatile process, there are certain materials that should never be put in a compost heap due to various reasons. These materials can have negative effects on the composting process, introduce harmful substances, attract pests, or simply take too long to decompose. Some common items that should be avoided in composting include:

  • Meat and fish
  • Dairy products
  • Oils and fats
  • Coal or charcoal ash
  • Plastic or synthetic materials
  • Yard waste treated with herbicides or pesticides

Meat and fish can attract unwanted pests, produce strong odors, and take a long time to break down. Dairy products can also create unpleasant smells and attract pests. Oils and fats can create a greasy, slimy compost pile and may not decompose properly. Coal or charcoal ash can contain harmful chemicals and alter the pH balance of the compost. Plastic or synthetic materials don’t break down and can contaminate the soil with microplastics. Yard waste treated with herbicides or pesticides can introduce chemicals that harm beneficial organisms and plants.

Weird Things You Can Compost

While there are items that should be avoided in a compost heap, there are also some unconventional items that can be composted successfully. These include:

  • Hair and nail clippings
  • Old cotton clothing and towels
  • Paper towels and napkins
  • Wine corks
  • Coffee filters
  • Vacuum cleaner dust

These items, though unusual, are organic and break down over time, contributing to the overall nutrient content of the compost. However, it’s important to note that composting these items may present challenges or potential risks. For example, long human hair or pet hair can form clumps, and vacuum cleaner dust may contain harmful particles, so caution should be exercised when composting these items.

Vegetables That Should Not Be Composted

While vegetables are generally great for composting, there are a few exceptions. Some vegetables that are not recommended for composting include:

  • Onion and garlic peels
  • Potato peels
  • Citrus peels
  • Tomato plants and leaves

These vegetables can take longer to decompose, attract pests, or potentially introduce harmful substances to the compost pile. However, it’s worth noting that these vegetables can still be composted if properly managed. Chopping them into smaller pieces or incorporating them into a hot composting system can help accelerate the decomposition process.

Reasons Not to Compost

While composting has numerous benefits, there may be reasons why someone may choose not to compost. Some potential reasons include:

  • Lack of space or resources for a compost heap
  • Concerns about odor or pests
  • Physical limitations or health conditions

However, it’s important to address common concerns or misconceptions about composting. For example, proper maintenance and balance can minimize odor and pest issues. Additionally, alternative environmentally-friendly waste disposal options, such as community composting programs or vermicomposting (composting with worms), can be considered.

Can You Put Branches in a Compost Bin?

Branches can be composted, but there are factors to consider when doing so. Large branches can take a considerable amount of time to break down, so it’s important to chop them into smaller pieces before adding them to the compost bin. It’s also beneficial to mix branches with other compostable materials such as leaves or grass clippings to help speed up decomposition. Additionally, using a compost bin with a larger capacity or opting for a chipper/shredder can make composting branches more manageable.


Composting is an effective way to reduce waste, minimize the use of chemical fertilizers, and improve the health of plants and soil. By understanding what not to put in a compost heap, we can ensure its effectiveness and avoid potential issues. It’s important to make informed decisions about composting, considering the materials that are ideal for composting and those that should be avoided. Responsible waste management is vital for a sustainable future, and composting plays a significant role in achieving that goal.

Question 1:
Answer: Meat, dairy products, and oily foods are not recommended to make compost.

Question 2:
Answer: Avoid composting onions, garlic, and citrus fruits.

Question 3:
Answer: Three things you shouldn’t compost are pet waste, diseased plants, and weeds with mature seeds.

Question 4:
Answer: Materials like plastics, metals, and synthetic chemicals are not allowed in compost.


About the author 

Jamie Willson

Hey there, I'm Jamie! As a Climate Scientist from MIT, I've spent years unraveling the complexities of global warming. My work ranges from conducting research on climate impacts to advising on environmental policies. I'm passionate about making the science of climate change accessible and actionable. Join me as we explore practical solutions to one of the biggest challenges facing our planet.