3 Bin Compost System (Fully Explained!)

  • By: Sam Richards
  • Date: August 31, 2023
  • Time to read: 11 min.

In today’s rapidly evolving ecological landscape, sustainable living practices are more than just buzzwords—they’re essential components of responsible stewardship of our planet. Among the many green initiatives we can adopt, composting stands out as a dual-purpose hero. It targets the dual objectives of waste reduction and soil enrichment, breathing life back into the earth. With multiple methods of composting available to suit various needs, the 3 bin compost system has emerged as a particularly effective and organized approach. Especially favored by those who have a regular influx of organic waste or a keen interest in gardening, this system promises efficiency and ease. As we journey through this guide, we will unpack the nuances and benefits of this stellar composting method.

What Is A Three Bin Compost System?

The 3 bin compost system is a structured and systematic approach to organic waste decomposition, designed to maximize efficiency and ease of use. Consisting of three adjacent composting bins, each compartment plays a pivotal role in the different phases of the composting lifecycle:

  • The First Bin: This is the starting point and serves as the repository for fresh organic waste. From kitchen scraps like vegetable peels, fruit remnants, and coffee grounds to garden waste such as fresh lawn clippings and green leaves, this bin kickstarts the decomposition process.
  • The Second Bin: Acting as the central hub of activity, this bin nurtures the transition of semi-decomposed matter from the first bin. Enhanced microbial activity here breaks down the organic matter more intensively, raising the temperature and accelerating the decomposition process. The waste, over time, undergoes a transformation, adopting a darker color and finer texture.
  • The Third Bin: This is the final resting place before the compost is ready for garden use. Transferred compost from the second bin continues its maturation journey here, stabilizing and curing to perfection. At this stage, microbial activity slows down, and the compost becomes a rich, dark, crumbly substance teeming with nutrients.

The beauty of this tripartite system is the continuous and organized composting flow it offers. While one bin is in the process of receiving fresh waste, another is busily decomposing, and the third is maturing the compost to its final garden-ready state.

Setting Up Your 3 Bin Compost System

Creating an efficient 3 bin compost system necessitates some preparation and thought. Here’s a detailed guide on how to set up this composting haven:

  • Choosing the Right Location:
    • Terrain: Start by identifying a spot with good drainage. A soggy composting area can waterlog the materials, leading to anaerobic decomposition, which isn’t optimal and can produce foul odors.
    • Accessibility: Consider the ease with which you can transport organic waste from your kitchen or garden. Closer proximity means less hauling of materials, making the process smoother.
    • Environmental Factors: Look for a location that receives a balanced mix of sun and shade. While direct sunlight can hasten decomposition, excessive exposure can dry out the pile. Conversely, too much shade can slow down the process.
  • Materials Needed:
    • Bins: There are various options available based on your budget and aesthetics. While ready-made composting bins are convenient, DIY enthusiasts might lean towards constructing their own from wooden pallets or wire mesh. Ensure the materials are sturdy and durable.
    • Essential Tools: A sturdy pitchfork or aerator will be indispensable for turning the compost. Additionally, durable garden gloves can protect your hands during the process. Keeping a water source nearby will also be beneficial, ensuring the compost remains at optimal moisture levels.
  • Construction Steps:
    • Dimensions: Each bin should ideally be about 3x3x3 feet. This size is considered optimal for maintaining the right temperature and moisture levels for decomposition. Smaller bins might not heat up adequately, while larger ones may not allow for proper aeration in the center.
    • Arrangement: Place the bins side by side in a row, ensuring each is easily accessible. This layout facilitates the smooth transitioning of compost from one bin to the next.
    • Accessibility: Ensure each bin has an opening that allows for easy turning and harvesting of the compost. Hinged lids or removable slats can be beneficial for this purpose.
    • Protection: Consider adding lids or covers to protect the compost from excessive rainfall or potential pests. If using a mesh design, the gaps shouldn’t be too wide, to prevent rodents from accessing the compost.

By ensuring a thorough setup, you create a foundation for a streamlined composting process that is both efficient and user-friendly.

How to Use the 3 Bin Compost System

Navigating the three-bin system may seem daunting initially, but with a bit of guidance, the process becomes intuitive. Here’s a detailed breakdown of how to effectively use each compartment of this composting system:

  • Bin 1: Fresh Inputs
    • Introducing Organic Waste: Begin by depositing your fresh organic waste into this bin. It serves as the primary collection point.
    • What to Add: Green waste is crucial here. Think of vegetable and fruit scraps, fresh lawn clippings, coffee grounds, and fresh leaves. These materials are rich in nitrogen and help fuel the decomposition process.
    • What Not to Add: Avoid introducing meats, dairy, oily foods, diseased plants, or any inorganic matter. These can attract pests and may slow down the decomposition process or produce undesirable odors.
    • Layering: For optimal results, try to alternate layers of green waste with brown waste (like dry leaves, straw, or cardboard). This not only balances the carbon-to-nitrogen ratio but also aids aeration.
    • Maintenance: Regularly moisten (without drenching) and turn the contents to introduce air and ensure even decomposition.
  • Bin 2: Active Composting
    • Transitioning: Once the first bin is full and its contents have started breaking down, it’s time to transfer this semi-decomposed material to Bin 2.
    • Aeration: Here, aeration is crucial. Regular turning using a pitchfork or aerator ensures that the compost gets the oxygen it needs, promoting aerobic decomposition.
    • Monitoring: Keep an eye on the moisture levels, ensuring the pile feels like a wrung-out sponge. Add water during dry spells and mix in brown materials if it gets too wet.
    • Decomposition Indicators: Over time, the materials will darken, decrease in volume, and produce heat – all signs of effective decomposition.
  • Bin 3: Maturation and Curing
    • Recognizing Transfer Time: Once the compost in Bin 2 is mostly dark, reduced significantly in volume, and no longer produces heat, it’s ready to be shifted to Bin 3.
    • Final Breakdown: In this bin, the compost undergoes its final stages of decomposition. The microbial activity slows down, and larger particles break down further.
    • Maintenance: Unlike Bin 2, Bin 3 doesn’t need as frequent turning. However, occasional turning can be beneficial to ensure even maturation.
    • Maturation Signs: Fully matured compost will be dark brown, have a crumbly texture similar to coarse soil, and emanate a pleasant, earthy scent.

Understanding the progression through the three bins helps maintain a continuous flow, ensuring that there’s always a batch of compost in preparation, active decomposition, and maturation simultaneously.

Troubleshooting Common Issues in the 3 Bin Compost System

While the three-bin composting system is designed for efficiency, like all organic processes, it may present challenges from time to time. Recognizing and addressing these issues promptly can make a world of difference in the quality and usability of your compost. Here’s a detailed look at common problems and their solutions:

  • Odor Problems:
    • Sour or Ammonia Smell: Often a sign that the pile is too wet or compacted. This leads to anaerobic decomposition.
      • Solution: Turn the compost more frequently to introduce air. If overly wet, add brown materials like dried leaves, straw, or cardboard to absorb excess moisture and balance the carbon-to-nitrogen ratio.
    • Rotten Smell: Typically indicates a lack of air and excessive moisture.
      • Solution: Aerate the compost pile by turning it. Incorporate coarse materials, like small twigs or straw, to create air pockets.
  • Pest Problems:
    • Flies or Gnats: Often attracted to exposed kitchen scraps.
      • Solution: Always cover fresh green materials with brown materials or partially decomposed compost. This will act as a barrier and deter these pests.
    • Rodents: They are usually attracted to food scraps, especially cooked food, meat, and dairy.
      • Solution: Ensure you’re only adding appropriate materials to your compost. If rodents persist, consider adding a wire mesh base or surrounding your compost bins with a fine mesh.
  • Slow Decomposition:
    • Cool Pile: If the compost doesn’t warm up, it could be due to a lack of nitrogen-rich green materials.
      • Solution: Introduce more green waste, such as fresh grass clippings or vegetable scraps.
    • Dry Pile: Insufficient moisture can stall the decomposition process.
      • Solution: Water the pile lightly, ensuring it reaches a consistency similar to a wrung-out sponge.
    • Compacted Pile: Lack of aeration can impede microbial activity.
      • Solution: Regularly turn and fluff the compost pile, and consider adding coarse brown materials to improve airflow.
  • Too Much Moisture:
    • Soggy Pile: Over-watering or excessive rainfall can cause the compost to become waterlogged.
      • Solution: Introduce brown materials to absorb some of the moisture. Shelter your compost bins with a cover or tarp during heavy rainfalls.
  • Uneven Decomposition:
    • Patchy Results: This indicates that certain parts of the pile are not getting enough air or have an imbalance of materials.
      • Solution: Regularly turn and mix the compost to ensure a consistent mixture and even decomposition throughout.

Addressing these challenges promptly will ensure your three-bin composting system works effectively, producing high-quality compost that your garden will love.

Harvesting and Using Your Compost

Once your compost has matured and achieved that dark, crumbly, earthy consistency in Bin 3, it’s time to harvest and utilize this black gold. Doing so effectively can amplify its benefits. Here’s a step-by-step guide:

  • Harvesting the Compost:
    • Visual Inspection: Before you begin, ensure the compost is uniformly dark brown and has a fine texture. There shouldn’t be any recognizable kitchen scraps or garden waste.
    • Sifting: For a finer consistency, especially if you’re using the compost for potting mixes or seed starting, you may wish to sift it through a compost screen or a mesh sieve. This will separate any larger, undecomposed materials from the finished compost.
    • Storing: If you aren’t going to use all the compost immediately, store the remainder in a dry, cool location. Use containers with lids to keep the compost moisture level stable and to deter pests.
  • Using the Compost:
    • Soil Amendment: The most straightforward way to use compost is to mix it into garden beds or planting areas. A 2 to 4-inch layer mixed into the topsoil can significantly enhance the soil’s texture, nutrient content, and microbial activity.
    • Potting Mix: Compost is an excellent addition to potting mixes. Combine it with other ingredients like coconut coir or perlite to create a well-draining, nutrient-rich medium for potted plants.
    • Lawn Care: Sprinkle a thin layer of compost over your lawn, a process known as “top-dressing.” This can help improve soil quality and boost grass health.
    • Mulch: While compost is finer than traditional mulches, it can still serve as a mulching layer around plants. It will help retain moisture, deter weeds, and as it breaks down further, feed the soil.
    • Compost Tea: This is a nutrient-rich liquid solution made by steeping mature compost in water. It can be used as a foliar spray or soil drench, offering plants a quick nutrient boost.
  • Safety Considerations:
    • Maturity: Ensure the compost is fully matured before use. Immature compost can rob plants of nitrogen and may contain harmful pathogens or weed seeds.
    • pH Level: Check the pH level of your compost if possible. While most compost is neutral to slightly acidic, significant deviations can affect plant growth. Adjusting with lime (to raise pH) or sulfur (to lower pH) might be necessary in such cases.
    • Diseased Plants: If you had added diseased plant matter to the compost, ensure the compost heated up sufficiently during the process. High temperatures kill most pathogens, but if you’re unsure, avoid using the compost around susceptible plants.

Harvesting and using compost is a rewarding culmination of your eco-friendly endeavors. Not only do you get to witness the transformation of waste into a valuable resource, but you also contribute to healthier plants and a more vibrant garden ecosystem.

Benefits of the 3 Bin Compost System

The three-bin composting system, while requiring a bit more space and initial setup, offers numerous advantages. Its structure and design promote more efficient and organized composting, yielding high-quality compost in relatively shorter timeframes. Here’s an in-depth look at its myriad benefits:

  • Continuous Composting:
    • Streamlined Process: With three bins in operation, there’s always a place to deposit fresh waste, another for active decomposition, and a third for curing and maturation. This organized flow ensures continuous compost production.
    • Volume Management: Because composting occurs in stages, each bin reduces the volume of its contents before transfer to the next, optimizing space usage.
  • Efficient Decomposition:
    • Optimized Conditions: By separating compost into different stages of decomposition, each bin can be managed to provide optimal conditions for its specific stage, ensuring efficient breakdown of materials.
    • Better Aeration: The system makes it easy to turn and aerate each bin’s contents, promoting aerobic decomposition, which is faster and less odoriferous than anaerobic methods.
  • High-Quality Compost:
    • Consistent Results: The systematic progression of waste through the three stages often results in a more consistent, high-quality end product.
    • Customizable Composting: Depending on your garden’s needs, you can adjust the time and conditions in each bin to produce compost with specific attributes, such as finer texture or higher nutrient content.
  • Pest and Odor Management:
    • Layered Design: Depositing fresh waste in the first bin and promptly covering it with brown materials or semi-decomposed compost helps deter pests and minimize odors.
    • Separate Stages: By segregating fresh waste from maturing compost, there’s less attraction for pests in the later stages, where the compost is nearing its garden-ready state.
  • Environmental Benefits:
    • Waste Reduction: With a designated place to continuously deposit organic waste, households can significantly reduce the volume of waste sent to landfills.
    • Carbon Sequestration: Composting organic matter captures carbon, reducing greenhouse gas emissions and helping to mitigate the effects of climate change.
    • Resource Conservation: Using homemade compost reduces the need for synthetic fertilizers, promoting sustainable gardening practices.
  • Economic Benefits:
    • Cost Savings: Producing your own compost means less money spent on garden soil enhancements and fertilizers.
    • Increased Garden Yield: Healthy, compost-enriched soil can boost garden productivity, leading to more abundant vegetable harvests and vibrant ornamental displays.

Incorporating a 3 bin compost system in your gardening routine not only underscores a commitment to sustainable living but also sets the stage for enhanced soil health, plant vitality, and a flourishing garden ecosystem.


The art of composting has been practiced for centuries, serving as a testament to humanity’s ability to harness nature’s cyclic processes. The three-bin compost system elevates this practice, blending tradition with strategy, and offering a structured and systematic approach to turning organic waste into a gardener’s treasure.

The benefits of this system stretch beyond the boundaries of our gardens. By adopting the three-bin method, we’re not just improving the health of our plants and soil but are also making a proactive stand for environmental conservation. With each scrap of waste we divert from landfills, we reduce methane emissions, a potent greenhouse gas. Moreover, the nutrient-dense compost produced minimizes the reliance on synthetic fertilizers, which often come with a heavy ecological footprint due to their manufacturing processes and potential for waterway pollution.

From an economic standpoint, the savings can be tangible. The initial investment in setting up the bins can quickly be offset by reduced expenditures on garden products and increased yields for those who cultivate food crops.

Furthermore, there’s an intrinsic reward in witnessing the transformative journey of waste materials. What once was discarded and overlooked takes on new life, nourishing the soil and promoting growth. This metamorphosis serves as a vivid metaphor for the potential of renewal and regeneration, encouraging us to rethink our relationships with waste and resources.

In embracing the three-bin compost system, we are not only investing in the well-being of our gardens but also fostering a deeper connection with the natural world, celebrating its innate wisdom and cycles. As more individuals adopt such sustainable practices, we move collectively towards a greener, more harmonious coexistence with our environment.

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