What to Put in a Compost Bin
Quick Answer: A healthy garden compost bin needs a balance of Greens (nitrogen-rich food scraps and grass clippings) and Browns (carbon-rich cardboard, dry leaves, and straw). Avoid adding too much meat, dairy, cooked oils, and pet waste to prevent bad odours and garden pests.
Composting is one of the most effective ways to reduce household food waste and enrich your garden soil naturally. However, if you are just starting out in the UK, knowing what can, and cannot, go into your heap can feel confusing.
Getting the balance right is key to creating nutrient-rich, dark compost without attracting pests or creating unpleasant smells. Here is your ultimate UK guide to getting it right the first time.
What Can You Put in a Compost Bin? (Greens vs Browns)
Composting relies on microbial decay, which thrives when you mix two essential elements: Greens (nitrogen-rich materials that provide moisture) and Browns (carbon-rich materials that add structure and oxygen). Use observational skills to decide how to balance them. If your compost contains a lots of green material, add in bulking material or browns to absorb moisture and eliminate smells from anaerobic conditions.
If your compost is too slow and lacks heat, it's too rich in carbon, so add in more moisture rich, green materials.
1. Nitrogen-Rich "Greens" (Moisture & Nutrients)
- Vegetable & Fruit Scraps: Peelings, cores, banana skins, and apple tops.
- Coffee Grounds & Tea Bags: Loose tea is best, or ensure tea bags are 100% plastic-free and biodegradable.
- Fresh Grass Clippings: Add in thin layers to prevent a slimy mess.
- Green Garden Trimmings: Prunings and soft plant stems.
- Crushed Eggshells: Adds vital calcium to your soil mix.
2. Carbon-Rich "Browns" (Structure & Airflow)
- Shredded Cardboard & Paper: Egg cartons, toilet roll tubes, and non-glossy cardboard boxes.
- Dead Leaves & Straw: Excellent for keeping the pile aerated.
- Bulking material. Specially designed to absorb moisture reduces smells and balance your compost.
What You Shouldn't Overload Your Compost Bin With?
Not everything from your kitchen or garden belongs in a composting bin. Too much of certain items cause bad odours, slow down breakdown times.
Items to add, (in small quantities).
- Meat, Fish & Bones: Attract pests and release severe foul odours during breakdown. Ensure they are finely chopped add your brown material and keep the lid firmly shut.
- Dairy Products & Cooked Oils: High fat and moisture content slow down decomposition and create anaerobic conditions. Small doses are fine, but don't overdo it.
- Pet Faeces (Cat or Dog Litter): Can carry harmful pathogens and parasites. Don't use this in compost intended for edible fruit or vegetable patches.
🚫Avoid completely
Rules of thumb: if it doesn't grow - leave it out!
- Non-organic and non-food items - Plastics, metals, batteries, rubber.
- Glossy Paper & Coated Packaging: Contains synthetic inks and plastic laminates that will not break down.
- Coal or Barbecue Ash: Contains heavy metals and chemicals that poison soil organisms.
3 Pro Tips for Better Composting
1. Use a Bulking Material
If you add a lot of wet kitchen waste, your compost can quickly become soggy and smelly. Adding a structured bulking material absorbs excess moisture, traps oxygen, and neutralises odours instantly.
2. Handle Compostable Packaging Correctly
While many UK brands now use compostable bin liners or packaging, do not toss them in whole filled with waste. Empty the contents out first, then tear up the bag separately before adding it in to ensure rapid breakdown.
3. Turn & Aerate Regularly
Compost needs oxygen to decompose effectively. If you are using a closed composter (such as the Biolan Quick Composter Eco 220), turn or mix the top 30cm of your compost every time you add fresh materials.
Frequently Asked Questions (FAQ)
How do I speed up my compost bin?
To accelerate breakdown, ensure your pile stays moist like a wrung-out sponge, keep the temperature up by insulated composting, and add a organic Composting Accelerator to boost microbial activity.
Can you put shredded cardboard in a compost bin?
Yes! Uncoated, non-glossy corrugated cardboard and toilet roll tubes make fantastic "Browns" that trap air pockets and balance wet food scraps.
Why does my compost bin smell like ammonia or rotten eggs?
If your compost smells bad, it means it is too wet or has too much nitrogen ("Greens"). Mix in plenty of bulking material, dry shredded cardboard or dead leaves, and turn the pile to introduce oxygen pockets.
Ready to Start Composting?
Whether you have a compact urban patio or a large allotment, choosing the right equipment makes all the difference.
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Explore our bulking material information to find out what it does.
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View our hot composters - ideal for composting all year round , even in winter.
- See How We Supported Ty Hafan with an Eco 220 composter
