What to Put In Your Compost Bin (The Do's)
Successfully turning waste into garden gold hinges on knowing precisely what goes into your compost bin. The fundamental principle is to add 'greens' (nitrogen-rich materials) and 'browns' (carbon-rich materials) in a balanced ratio, alongside moisture and air. This aerobic process breaks down organic matter efficiently. Aim for roughly a 50/50 mix, though slightly more browns is often beneficial to prevent sogginess.
Green materials include fresh grass clippings (in thin layers to avoid matting), fruit and vegetable peelings, coffee grounds and tea bags (remove staples), and plant trimmings. These provide essential nitrogen and moisture. Brown materials, such as dried leaves, straw, shredded cardboard and newspaper (avoid glossy print), twigs, and sawdust (from untreated wood), supply carbon and create air pockets. Incorporating materials like ericaceous compost components, if available, can enrich the final product for specific plant needs. Many gardeners find composting a garden’s yield, such as fallen leaves or spent annuals, immensely rewarding.
Layering and Aeration
Start your compost bin with a layer of coarser brown material, like small twigs, to ensure good drainage and airflow from the base. Subsequent layers should alternate between greens and browns. For instance, a layer of vegetable scraps can be topped with a layer of dried leaves. Turning or aerating the compost pile regularly, perhaps once every few weeks using a fork or aerator tool, is vital. This introduces oxygen, preventing anaerobic conditions that lead to unpleasant smells and slow decomposition. Without sufficient air, the beneficial microbes struggle to work.
Ensure adequate moisture: Your compost heap should feel like a wrung-out sponge. Too dry, and decomposition slows dramatically; too wet, and it becomes a foul-smelling, slimy mess. Add water if dry, or more brown materials if too damp.
The Role of Compost Worms
For faster, more contained composting, particularly in smaller spaces or for kitchen waste, consider vermicomposting using compost worms (like red wigglers). These specialized worms consume food scraps and produce nutrient-rich worm castings, a superb fertiliser. When setting up a worm bin, ensure you include bedding material like shredded newspaper or coir, and add worm-friendly greens like fruit and vegetable scraps, coffee grounds, and tea leaves. Avoid citrus in large quantities, as worms can be sensitive to its acidity.
Materials to include:
- Grass clippings (thin layers)
- Fruit and vegetable scraps
- Coffee grounds and tea bags
- Eggshells (crushed)
- Plant trimmings (disease-free)
- Shredded newspaper and cardboard (non-glossy)
- Dried leaves and straw
- Small twigs and prunings
- Sawdust (from untreated wood)
What to Leave Out of Your Compost (The Don'ts)
While many organic materials can be composted, certain items can disrupt the process, attract pests, spread disease, or simply not break down effectively. Avoiding these ‘don’ts’ is just as important as knowing the ‘do’s’ for creating healthy compost.
Avoiding Pests and Pathogens
Meat, fish, dairy products, and oily foods are prime culprits for attracting rodents, flies, and other unwelcome visitors. They also tend to decompose anaerobically, leading to putrid odours. While some advanced composting systems can handle these, they are best avoided in standard garden compost bins. Similarly, diseased plants or weeds that have gone to seed should be excluded. If these end up in your compost, you risk spreading pests and diseases back into your garden when you use the finished compost. Always check that your compost bins are designed to deter pests, especially if you are composting a garden's yield.
Materials to avoid:
- Meat, fish, bones
- Dairy products (milk, cheese, yoghurt)
- Oily or greasy foods
- Diseased plant material
- Weeds that have set seed
- Pet faeces (dog, cat)
- Coated cardboard or glossy paper
- Treated wood or sawdust
- Synthetic materials
Stubborn Materials and Chemical Contaminants
Larger, woody items like branches or thick stalks can take a very long time to decompose in a standard compost bin. While small twigs are beneficial, larger pieces should be chipped or composted separately. Avoid adding anything that is not organic, such as plastics, metals, or glass. Even materials that seem organic but have been treated with chemicals, like treated sawdust or varnished wood, should be kept out. If you’re considering using multi-purpose compost for specific needs, ensure it’s suitable and free from contaminants.
When considering how to start composting, remember that patience is key. Some materials, like citrus peels in large quantities, can slightly alter the pH of the compost, which might not be ideal for all plants. It's generally better to use them in moderation. Similarly, while compost bags are useful for bulk purchasing, ensure they are biodegradable or reusable if possible, and empty them fully before composting.
When in doubt, leave it out: If you're unsure whether an item is suitable for composting, it's safer to place it in your general waste or recycling rather than risk contaminating your compost heap.
The impact of pet waste: Dog and cat faeces can contain pathogens that are harmful to humans and may not be killed by the composting process in a typical garden bin. It's best to dispose of this waste separately.
Troubleshooting Common Composting Problems
Even with the best intentions, compost piles can sometimes present challenges. Understanding the common issues and their solutions will help you maintain a healthy, efficient composting system. Problems often arise from an imbalance in the greens/browns ratio, moisture levels, or aeration.
Addressing Odours and Sliminess
A common issue is a strong, ammonia-like or rotten smell, often accompanied by a slimy texture. This usually indicates too much nitrogen (too many 'greens') or insufficient aeration. The pile is likely working anaerobically. To fix this, turn the pile thoroughly to introduce air. Add a generous amount of brown materials, such as shredded cardboard, dried leaves, or straw, to absorb excess moisture and balance the nitrogen. Ensure you are not adding large quantities of grass clippings without mixing them with browns. This is a key element of successful composting, whether you are using best compost bins or a simple heap.
Dealing with Dryness and Slow Decomposition
Conversely, a pile that remains dry and shows little sign of decomposition may lack moisture or nitrogen. If the material feels dry and brittle, gradually add water while turning the pile to distribute it evenly. If it's decomposing very slowly, you might need more nitrogen-rich green materials. Consider adding more kitchen scraps, fresh grass clippings, or even a small amount of well-rotted manure if available. Chop larger items into smaller pieces, as this increases the surface area for microbes to work on.
What to check:
- Smell: Earthy smell = good; Rotten/ammonia smell = too wet/too many greens/no air.
- Moisture: Squeezes into a ball but crumbles = ideal; Water drips out = too wet; Falls apart = too dry.
- Temperature: A healthy, active pile will heat up. A cold pile indicates slow or no activity.
When creating your own compost, especially from composting a garden's waste, patience is a virtue. The decomposition time can vary significantly based on the materials used, the size of the pile, and environmental conditions. Using compost worms can significantly speed up the process for specific materials. Always ensure you are aiming for a crumbly, dark, earthy-smelling finished product, often referred to as 'black gold', which is ideal for enriching soil.
Monitor the temperature: An active compost pile generates heat. If your pile isn't heating up, it might be too small, too dry, lack nitrogen, or need turning. A hot pile also breaks down faster and kills weed seeds and pathogens.
Balancing act: The ideal composting do's and don'ts is about achieving balance. Think of it as a living ecosystem that needs the right conditions to thrive. Regularly assessing the state of your compost and making minor adjustments can prevent major problems down the line.