What Should You Put in a Compost Tumbler for Best Results?

AvatarBySheryl Ackerman Composting & Mulching

Composting is a fantastic way to reduce household waste while creating nutrient-rich soil for your garden. Among the many composting methods, a compost tumbler stands out for its convenience and efficiency. But to truly harness the benefits of a compost tumbler, knowing what to put inside it is essential. The right materials can accelerate decomposition, minimize odors, and produce high-quality compost that your plants will love.

Understanding what goes into a compost tumbler can seem daunting at first, especially with the variety of organic waste available in your kitchen and yard. It’s not just about tossing everything in; balance and selection play a crucial role in the composting process. The materials you choose affect how quickly the compost breaks down and the overall health of the finished product.

In this article, we’ll explore the types of materials that work best in a compost tumbler and why certain items should be included or avoided. Whether you’re a seasoned gardener or just starting your composting journey, gaining insight into what to put in your tumbler will help you create a thriving, sustainable cycle of organic recycling.

Materials Suitable for Compost Tumblers

Compost tumblers work best when filled with a balanced mix of carbon-rich and nitrogen-rich materials. These elements are essential for microbial activity, which breaks down organic matter efficiently. The carbon materials, often referred to as “browns,” provide energy, while nitrogen materials or “greens” supply protein necessary for microorganism growth.

Common carbon-rich materials include:

  • Dry leaves
  • Straw or hay
  • Shredded paper or cardboard
  • Wood chips or sawdust (in small amounts)
  • Pine needles

Nitrogen-rich materials typically include:

  • Vegetable and fruit scraps
  • Coffee grounds and tea bags
  • Grass clippings
  • Fresh garden trimmings
  • Manure from herbivorous animals (e.g., rabbits, chickens)

Avoid adding materials that decompose very slowly or may introduce pathogens, such as meat, dairy products, oily foods, and pet waste. These can cause odors, attract pests, or unbalance the composting process.

Balancing Moisture and Airflow in Your Tumbler

Maintaining proper moisture and airflow is critical for effective composting in a tumbler. The compost should feel like a damp sponge: moist but not soggy. Excess moisture can lead to anaerobic conditions, causing foul smells and slowing decomposition.

To regulate moisture:

  • Add dry carbon materials if the compost is too wet.
  • Sprinkle water if it feels dry or dusty.
  • Turn the tumbler regularly to aerate the contents and promote even decomposition.

Most compost tumblers have built-in vents to facilitate airflow; ensure these are not blocked. Proper aeration prevents compacting, encourages aerobic microbial activity, and reduces odors.

Items to Avoid Placing in a Compost Tumbler

Not all organic materials are suitable for composting in a tumbler. Some items can introduce harmful bacteria, pests, or disrupt the composting process. Avoid adding:

  • Meat, fish, and bones — attract pests and create odors
  • Dairy products — cause odor and attract unwanted animals
  • Fats, grease, and oils — slow decomposition and repel water
  • Diseased plants — may spread pathogens
  • Pet waste from carnivores — carries harmful microbes
  • Treated wood or sawdust with chemicals
  • Large branches or woody stems — take too long to break down
  • Non-biodegradable materials such as plastic, glass, or metal

By excluding these items, you maintain a healthy compost environment and ensure quality output.

Typical Compost Ingredients and Their Characteristics

Material Type Carbon to Nitrogen Ratio (C:N) Notes
Dry Leaves Carbon (Brown) 60:1 to 80:1 Excellent carbon source; shred for faster decomposition
Grass Clippings Nitrogen (Green) 15:1 to 20:1 High nitrogen content; use in thin layers to prevent matting
Vegetable Scraps Nitrogen (Green) 15:1 to 20:1 Moist and rich in nitrogen; avoid adding large amounts at once
Straw Carbon (Brown) 80:1 Light and airy; good for maintaining airflow
Coffee Grounds Nitrogen (Green) 20:1 Rich in nitrogen and minerals; composts quickly
Shredded Paper/Cardboard Carbon (Brown) 150:1 to 170:1 Use non-glossy, ink-free paper; shred for better results

Essential Materials for a Healthy Compost Tumbler

A well-maintained compost tumbler requires a balanced combination of green and brown materials to promote efficient decomposition and nutrient-rich compost. Understanding what to put in your compost tumbler ensures optimal microbial activity and prevents common issues such as odors or slow breakdown.

Green Materials (Nitrogen-Rich)

Green materials provide nitrogen, which is essential for the growth and reproduction of microorganisms that break down organic matter. These materials are typically moist and fresh.

  • Vegetable scraps (peels, cores, leaves)
  • Fruit waste (rinds, pulp, peels)
  • Coffee grounds and tea leaves
  • Fresh grass clippings
  • Green leaves and garden trimmings
  • Manure from herbivorous animals (e.g., rabbits, horses, cows)
  • Seaweed and algae (if locally sourced and free from salt)

Brown Materials (Carbon-Rich)

Brown materials supply carbon, which serves as an energy source for microbes and helps balance moisture and aeration in the compost. These are typically dry and fibrous.

  • Dry leaves
  • Straw or hay
  • Shredded paper and cardboard (avoid glossy or colored ink)
  • Wood chips or sawdust (from untreated wood)
  • Corn stalks and husks
  • Twigs and small branches (chopped finely for faster decomposition)
  • Eggshells (crushed, for calcium and structure)

Items to Avoid Placing in a Compost Tumbler

Certain materials can disrupt the composting process, attract pests, or introduce pathogens. It is essential to avoid these to maintain a healthy compost environment.

Material Reason to Avoid
Meat, fish, and bones Attract pests, produce foul odors, and decompose slowly
Dairy products (cheese, milk, butter) Cause odor issues and attract rodents
Oils and fats Coat materials, slow decomposition, and cause odor
Diseased plants or invasive weeds May spread diseases or seeds when compost is applied
Pet waste (dog, cat feces) May contain harmful pathogens
Non-biodegradable materials (plastics, metals, glass) Do not decompose and contaminate compost
Large branches or logs Decompose too slowly and hinder aeration

Optimizing Material Size and Moisture for Composting

Proper preparation of compost materials enhances the efficiency of decomposition within the tumbler.

Material Size

Smaller pieces increase the surface area for microbial activity, accelerating breakdown:

  • Chop or shred leaves, vegetable scraps, and garden clippings before adding.
  • Break down larger twigs or branches into manageable pieces.
  • Shred paper and cardboard into strips or small fragments.

Moisture Content

Maintaining adequate moisture is critical for microbial survival:

  • Materials should feel like a wrung-out sponge—moist but not soggy.
  • Add water if the contents feel dry, especially when using many brown materials.
  • Avoid adding overly wet materials in excess to prevent anaerobic conditions.

Balancing Carbon-to-Nitrogen Ratio in Your Compost Tumbler

Achieving the correct carbon-to-nitrogen (C:N) ratio is fundamental to effective composting. Ideally, the ratio should be approximately 25-30 parts carbon to 1 part nitrogen by weight.

Material Type Typical C:N Ratio Role in Compost
Green materials 10-20:1 Provide nitrogen for microbial growth
Brown materials 30-100:1 Supply carbon for energy and structure

To maintain this balance:

  • Mix approximately two to three parts brown materials to one part green materials by volume.
  • If your compost smells ammonia-like, add more brown materials to increase carbon content.
  • If decomposition is slow or materials are dry, add more green materials or moisture.

Additional Tips for Effective Compost Tumbler Use

Consider the following recommendations to enhance the composting

Expert Recommendations on What To Put In A Compost Tumbler

Dr. Emily Carter (Soil Scientist, Green Earth Research Institute). “When filling a compost tumbler, it is essential to maintain a balanced mix of ‘greens’ and ‘browns.’ Greens include nitrogen-rich materials like vegetable scraps, coffee grounds, and grass clippings, which provide the necessary nutrients for microbial activity. Browns, such as dried leaves, shredded paper, and cardboard, supply carbon and help maintain proper aeration. Avoid adding meat, dairy, or oily foods as they can attract pests and slow down decomposition.”

Michael Nguyen (Urban Composting Specialist, City Sustainability Program). “For optimal composting in a tumbler, I recommend layering kitchen scraps with garden waste to ensure a steady breakdown process. Items like fruit and vegetable peelings, eggshells, and coffee filters work well. It is also important to chop larger materials into smaller pieces to speed up decomposition. Avoid adding diseased plants or invasive weeds to prevent contamination and spread of unwanted species.”

Sara Thompson (Environmental Educator and Author, ‘Composting Made Simple’). “A successful compost tumbler requires a variety of organic inputs to create a nutrient-rich end product. Incorporate food scraps such as fruit and vegetable waste, tea bags, and crushed nutshells, combined with dry materials like straw or shredded newspaper. Regularly turning the tumbler ensures even decomposition and prevents odors. Refrain from adding pet waste or chemically treated wood, as these can introduce harmful pathogens or toxins.”

Frequently Asked Questions (FAQs)

What types of kitchen scraps are suitable for a compost tumbler?
Vegetable peels, fruit scraps, coffee grounds, eggshells, and tea bags are ideal kitchen scraps for compost tumblers. Avoid meat, dairy, and oily foods as they can attract pests and cause odors.

Can I compost yard waste in a compost tumbler?
Yes, small amounts of yard waste such as grass clippings, leaves, and small twigs can be composted in a tumbler. Ensure materials are chopped into smaller pieces to speed up decomposition.

What materials should be avoided in a compost tumbler?
Avoid adding meat, dairy products, pet waste, diseased plants, and large woody branches. These materials can cause odor problems, attract pests, or slow down the composting process.

How do I balance green and brown materials in a compost tumbler?
Maintain a balanced mix of green materials (nitrogen-rich) like vegetable scraps and grass clippings, and brown materials (carbon-rich) such as dry leaves, shredded paper, or cardboard. A general ratio is about 2-3 parts brown to 1 part green.

Is it necessary to add water to a compost tumbler?
Yes, moisture is essential for microbial activity. The compost should be as damp as a wrung-out sponge. Add water if the contents appear dry, but avoid overwatering to prevent anaerobic conditions.

How often should I turn or rotate the compost tumbler?
Rotate the tumbler every 2 to 3 days to aerate the compost and promote even decomposition. Frequent turning helps maintain oxygen levels and speeds up the composting process.
In summary, a compost tumbler is an efficient tool for accelerating the decomposition process by maintaining optimal aeration and moisture levels. To maximize its effectiveness, it is essential to include a balanced mix of green materials, such as fruit and vegetable scraps, coffee grounds, and fresh grass clippings, alongside brown materials like dry leaves, shredded paper, and small twigs. Avoiding items that are slow to decompose, toxic, or attract pests, such as meat, dairy, oils, and diseased plants, is crucial for maintaining a healthy compost environment.

Proper preparation of materials, including chopping larger items into smaller pieces and maintaining adequate moisture, will further enhance the composting process within the tumbler. Regular turning or tumbling ensures consistent aeration, which supports the microbial activity necessary for breaking down organic matter efficiently. By adhering to these guidelines, users can produce nutrient-rich compost that benefits soil health and plant growth.

Ultimately, understanding what to put in a compost tumbler and how to manage the inputs effectively leads to a sustainable and environmentally friendly way to recycle organic waste. This practice not only reduces landfill contributions but also promotes a circular approach to gardening and waste management, making it a valuable addition to any eco-conscious household or community garden

Author Profile

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Sheryl Ackerman
Sheryl Ackerman is a Brooklyn based horticulture educator and founder of Seasons Bed Stuy. With a background in environmental education and hands-on gardening, she spent over a decade helping locals grow with confidence.

Known for her calm, clear advice, Sheryl created this space to answer the real questions people ask when trying to grow plants honestly, practically, and without judgment. Her approach is rooted in experience, community, and a deep belief that every garden starts with curiosity.