What Takes The Longest To Compost? 10 Powerful Facts That Might Surprise You

Composting is a great way to reduce waste and nourish your garden, but have you ever wondered what takes the longest to compost? While most organic materials break down relatively quickly, there are a few things that seem to defy the composting process. In this article, we will explore the surprising items that take the longest to compost, shedding light on the importance of mindful waste management and the true art of decomposition. Get ready to discover the unlikely candidates that will make you rethink what you toss into your compost bin.

What Takes The Longest To Compost?


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Composting is a wonderful way to reduce waste and create nutrient-rich soil for your garden. However, not all materials decompose at the same rate. Some items take longer to break down and require more time and effort to turn into compost. In this article, we will explore the factors that affect composting time and discuss ten materials that take the longest to compost.

Factors Affecting Composting Time

Several factors can influence the time it takes for materials to compost. The main factors include the size and density of the item, its carbon-to-nitrogen ratio, the presence of harmful chemicals, and the composting method used. Understanding these factors is crucial in determining how long it will take for certain materials to break down fully.

What Takes The Longest To Compost?

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1. Wood

Wood is a commonly used material in various forms, such as sawdust, wood chips, or branches. While small wood chips and sawdust can decompose relatively quickly, larger pieces of wood can take a significant amount of time to break down completely. The size and density of wood play a vital role, with thicker pieces requiring more time for composting. It is recommended to shred or chip wood into smaller sizes to accelerate the decomposition process.

1.1 Hardwood

Hardwood, including materials like oak or maple, takes longer to compost compared to softwood. This is primarily due to its higher density and slower decay rate. Hardwood can take anywhere from several months to several years to fully decompose, depending on the size and conditions within the compost pile.

1.2 Softwood

Softwood, such as pine or cedar, decomposes faster than hardwood due to its lower density. However, it still takes longer to break down compared to many other compostable materials. Proper shredding and turning of softwood can help speed up the composting process.

2. Animal Bones

Animal bones are rich in calcium and other minerals, making them valuable additions to compost. However, they are also incredibly slow to break down. Bones can take several years to decompose fully, depending on their size and the composting conditions. To accelerate the decomposition process, consider grinding or crushing the bones before adding them to the compost pile.

What Takes The Longest To Compost?

3. Eggshells

Eggshells, despite being fragile and seemingly easy to break down, can take a surprisingly long time to compost. This is because they are primarily composed of calcium carbonate, which does not decompose as quickly as other organic materials. To speed up the process, crush the eggshells into small pieces before adding them to your compost pile.

4. Citrus Peels

While fruits and vegetable scraps generally compost relatively quickly, citrus peels are an exception. The high acidity and oil content of citrus peels make them resistant to decomposition. It can take several months for citrus peels to break down completely. Cutting the peels into smaller pieces or using a hot composting method can help expedite the process.



What Takes The Longest To Compost

5. Pine Needles

Pine needles, also known as pine straw, are commonly used for mulching and ground cover. They are slow to compost due to their tough and waxy structure. Pine needles can take anywhere from one to three years to decompose fully. If you wish to incorporate pine needles into your compost, shred them into smaller pieces to speed up the decomposition process.

6. Shells

Whether it’s seashells or nutshells, shells take a long time to compost. Their hard and durable composition makes them resistant to decay. Depending on the size of the shells, it can take several years for them to fully decompose. To accelerate the process, crush the shells into smaller fragments or consider using them for other purposes, such as drainage in pots or as decorative accents.

7. Corn Cobs

Corn cobs are high in lignin, a complex polymer that takes time to break down. Due to their density and woody nature, corn cobs decompose slowly. Depending on the size and conditions, it can take anywhere from several months to a few years for corn cobs to fully compost. Breaking the cobs into smaller pieces or shredding them will help expedite the process.

8. Avocado Pits

Avocado pits are incredibly hard and resistant to decomposition. They can take several years to break down completely, even under ideal composting conditions. Crushing the pits or grinding them into smaller pieces will help speed up composting, but it will still require a significant amount of time and patience.

9. Onion Skins

While onion skins are technically compostable, they decompose at an extremely slow pace. The outer layers of onion skins are tough and resistant to decay. It may take several months for onion skins to break down fully. Chopping the skins into smaller pieces or using a hot composting method can help accelerate the process.

10. Paper Products

Paper products, such as cardboard or newspaper, can take a considerable amount of time to compost fully. This is because they are often treated with chemicals during the manufacturing process. While the actual decomposition time varies depending on the specific type of paper product, it can range from several weeks to several months. Be sure to shred paper materials into smaller pieces before adding them to your compost pile to speed up the process.

Is Composting the Same as Decomposing?

While the terms “composting” and “decomposing” are often used interchangeably, they are not synonymous. Both are natural processes that break down organic matter, but they differ in several key aspects, including the conditions under which they occur, the speed of the process, and the end products.


Decomposition is a natural process that occurs ubiquitously in nature. When an organic material, such as a fallen leaf, animal carcass, or food scrap, is left exposed to the elements, it will eventually break down through the action of bacteria, fungi, and other microorganisms. This process occurs with no human intervention and can happen in a range of environments, from forests and meadows to water bodies and deserts.

Composting, on the other hand, is a managed process that seeks to accelerate the natural decomposition of organic matter. It is generally performed in a controlled environment, such as a compost bin or pile, where conditions like moisture, temperature, and aeration can be closely monitored and adjusted to optimize decomposition rates.

Speed of the Process

Decomposition in nature can take an unpredictable amount of time, depending on factors like weather conditions, the presence of decomposers, and the type of organic material. For instance, a fallen tree in a rainforest might decompose much faster than a similar tree in an arid climate due to the abundance of moisture and decomposers.

Composting aims to speed up the decomposition process by providing ideal conditions for microbial activity. By maintaining the correct ratio of “green” (nitrogen-rich) and “brown” (carbon-rich) materials, as well as adequate moisture and aeration, composting can produce a rich, humus-like material in a matter of weeks to months, as opposed to the years it might take in nature.

End Products

The end product of natural decomposition varies widely depending on the conditions and materials involved. In aquatic environments, for instance, decomposition can result in a muddy accumulation of organic material at the bottom of a body of water. In forests, decomposition enriches the soil but may also leave behind materials that take longer to break down, like bones or wood.

In contrast, composting yields a uniform end product: compost, a nutrient-rich, soil-like material that is ideal for gardening and agriculture. Because the composting process is controlled and managed, the end product is generally free from pathogens, weed seeds, and harmful chemicals, making it safe and beneficial for plant growth.

Human Involvement

Another significant difference is the level of human involvement. Decomposition will occur naturally without human intervention, while composting is a process that is initiated and managed by humans. The act of composting involves collecting organic waste, balancing the materials, and turning the pile to ensure even decomposition, among other activities.

Environmental Impact

While both composting and decomposition recycle organic material back into the Earth, composting has a more direct positive environmental impact. Managed composting systems can reduce the volume of waste sent to landfills and incinerators, thereby reducing greenhouse gas emissions. Moreover, compost can replace synthetic fertilizers, reducing the dependency on fossil fuels and mitigating water pollution from agricultural runoff.

In summary, while both composting and decomposing serve to break down organic material, composting is a more controlled, efficient, and beneficial process. Understanding the distinctions between the two can guide individuals and communities in making more sustainable choices for waste management and soil fertility.

Items That Are Virtually Impossible to Compost

When it comes to composting, understanding what can and cannot be composted is vital. Some items are virtually impossible to compost due to their nature or because they contain harmful substances. Here’s a closer look at these items, the reasons they’re difficult to compost, and the hypothetical effects if they were compostable.


Why It’s Difficult

Plastics are petroleum-based and do not decompose in a composting environment. They require specific recycling processes or will otherwise remain in the environment for hundreds of years.

Relevant Facts

Some bioplastics claim to be compostable, but they often require industrial composting facilities to break down completely. In home composting setups, they may not decompose adequately.

Hypothetical Effects if Compostable

If plastics were compostable, it would revolutionize waste management and significantly reduce landfill and ocean pollution. However, it could potentially introduce other problems, such as how the composted plastics would interact with soil ecosystems and whether they would release any harmful substances during decomposition.


Why It’s Difficult

Metals like aluminum, steel, or copper don’t break down in a compost pile because they are not organic materials. They require a different recycling process.

Relevant Facts

Some metals can be toxic to plants and soil microorganisms, disrupting the composting process and potentially contaminating the soil.

Hypothetical Effects if Compostable

If metals were compostable, the need for specialized metal recycling facilities would be diminished. However, the implications for soil quality and plant health would need careful consideration, as metals could release potentially toxic ions during the decomposition process.


Why It’s Difficult

Glass, like metal, is inorganic and does not decompose. It remains inert in a compost pile and will not break down into a form that can be used for soil enrichment.

Relevant Facts

Broken glass can be hazardous to handle and may cause injury when turning or spreading your compost.

Hypothetical Effects if Compostable

If glass could be composted, it would simplify waste management procedures. But the question would remain about its impact on soil structure and whether broken-down glass components might affect plant growth or soil-dwelling organisms negatively.

Rubber and Latex

Why It’s Difficult

Rubber and latex products, such as tires or gloves, are resistant to microbial degradation due to their complex molecular structure.

Relevant Facts

Rubber items may also contain additives and chemicals that can be harmful to soil health.

Hypothetical Effects if Compostable

If rubber and latex were compostable, it would alleviate a significant burden from landfill sites where these materials usually end up. However, the potential release of chemical additives during decomposition could be a concern for soil and water quality.

Dairy and Meat Products

Why It’s Difficult

While not entirely “impossible” to compost, dairy and meat products are generally avoided in home composting systems. They decompose very slowly and attract pests.

Relevant Facts

If you are interested in composting these materials, specialized systems like Bokashi composting can be effective but are not suited for traditional compost piles.

Hypothetical Effects if Compostable

If dairy and meat products were easily compostable, it would make household waste management more efficient and less wasteful. However, concerns about pathogens and the nutritional balance of the resulting compost would need to be addressed.

Coated or Laminated Paper

Why It’s Difficult

Paper that has been coated or laminated often contains plastics or waxes that make it resistant to decomposition.

Relevant Facts

Coated paper items can also introduce toxins into your compost pile, potentially making the finished compost unsuitable for use in organic gardening.

Hypothetical Effects if Compostable

If coated or laminated papers were compostable, it would ease the strain on paper recycling facilities and reduce landfill waste. The impact on soil health would be largely dependent on the nature of the coatings and whether they released harmful substances during decomposition.

Synthetic Fabrics

Why It’s Difficult

Fabrics like polyester, nylon, and acrylic are made from synthetic fibers that do not break down in a compost pile.

Relevant Facts

Not only do these fabrics fail to decompose, but they can also release microplastics into the environment as they break down into smaller pieces.

Hypothetical Effects if Compostable

If synthetic fabrics were compostable, it would significantly reduce waste in landfills and potentially alleviate microplastic pollution. However, consideration would need to be given to any chemical residues that could remain in the compost and affect soil health.

By examining these items and pondering the hypothetical scenarios where they could be composted, we gain insights into the complexity and impact of composting on waste management and environmental sustainability. While the ability to compost these materials might simplify waste handling, it could also introduce new challenges in terms of soil and environmental health.

What Takes The Longest To Compost:  Conclusion

In conclusion, the world of composting is nuanced, and the breakdown time of materials is no exception to this complexity. While some items like food scraps and green leaves might decompose relatively quickly, others such as wood chips, bones, and certain types of shells can linger in your compost pile for an extended period. It’s crucial to recognize that factors like size, density, and chemical composition all play a vital role in determining how long it takes for a material to fully compost.

Specifically, wood, due to its dense and fibrous structure, can take several months or even years to decompose fully. Bones and eggshells, rich in calcium and other minerals, also need a long timeframe to break down. Citrus peels, pine needles, and avocado pits are notorious for their lengthy decomposition timelines due to their tough, waxy, or oily surfaces, which make it difficult for microorganisms to penetrate them quickly. Even more ubiquitous items, such as corn cobs and onion skins, can be stubborn, requiring a considerable amount of time due to their dense cellulose structures. Paper products, usually considered easy to compost, can also take a long time if they are coated or laminated.

Understanding these dynamics is not just academic; it has practical implications for anyone seeking to engage in sustainable waste management through composting. Knowledge of decomposition rates can guide you in layering your compost pile effectively, pairing quicker-decomposing materials with those that take longer to break down. This can optimize the composting process, creating a more efficient and effective system. Additionally, certain preparation techniques, like shredding wood or crushing shells and bones, can speed up the composting process by increasing the surface area available for microbial activity.

While it may be tempting to shy away from composting these slow-to-decompose items, they still offer valuable contributions to the quality of your compost. Slow-decomposing items often add essential minerals and structure to the finished compost. Therefore, the best approach is not to exclude these items but to manage them effectively. This requires patience and a commitment to long-term sustainability over quick results.

In summary, managing a compost pile is an art and a science, influenced by a range of factors from chemical composition to environmental conditions. Taking the time to understand the individual characteristics of the materials you are composting can lead to a more effective and efficient composting process, benefitting not just your garden, but also contributing to a more sustainable planet.

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Sharron Nixon

Hi there! I'm Sharron, the face behind Composting Guru. I'm passionate about helping you discover and unlock the earth's secret recipe - composting. With our curated content, expert advice, and top-tier tools, I'm here to guide you in mastering the art of composting. Whether you're searching for the perfect composter or seeking tips on creating nutrient-rich compost, you've come to the right place. Together, we'll transform your waste into garden gold. Join me on this journey as we dive deep into the world of composting and unlock its true potential. Let's make the Earth thrive with Composting Guru!

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