How to Speed Up Composting:

5 Tips for Faster Decomposition

Homemade compost can take several months or longer to become usable. However, with the right techniques you can create rich crumbly compost in just a few weeks!

In a nutshell, to compost faster, build a larger pile, maintain a 20:1 ratio of brown to green materials, shred organic waste, regularly aerate the pile, and keep it as moist as a damp sponge. These steps promote microbial activity and heat, reducing composting time to 3–6 weeks.

This guide shares expert-tips from our team at Arboretum, with over 40 years of hands-on experience helping gardeners grow better. Our easy-to-follow tips are for both beginner or experienced gardeners to help get your compost pile cooking!

How to Speed Up Composting:

1. Size Matters: Make a Larger Compost Pile

The way your organic waste turns into nutrient-rich fertiliser for your plants is with heat. The bigger the pile, the better it retains heat, an essential component in speeding up decomposition. A heap around 1 cubic metre is ideal. Larger piles also hold moisture better and allow microbes to thrive, turning waste into usable fertiliser more quickly.

2. Get the Right Ratio of Browns to Greens

Compost needs a balance of carbon-rich “browns” (dry leaves, cardboard, straw) and nitrogen-rich “greens” (grass clippings, food scraps, manure). Aim for a ratio of around 20:1 (browns to greens). 

If your pile isn’t breaking down fast, add more browns like:

• Shredded cardboard
  
• Dry leaves
  
• Sawdust or wood chips
• Add a compost maker like Garotta to help speed up the process

3. Shred and Chop Everything

Smaller particles compost faster. Shredding your browns and chopping food scraps increases surface area and allows microbes to work more efficiently. As a bonus, it also introduces air pockets that improve airflow within the pile.

Top tip: A garden shredder or mulching mower can save time and effort.

4. Turn and Aerate Your Compost Regularly

Oxygen is crucial for aerobic microbes—the good bacteria responsible for rapid decomposition. Use a garden fork or compost aerator to turn your pile every 1–2 weeks.

This:

• Adds oxygen
• Controls temperature
  
• Prevents foul odours
  
• Helps break down material evenly

5. Maintain the Right Moisture Level

Your compost pile should feel like a damp sponge, moist but not soggy. Dry piles slow down, while overly wet piles can turn anaerobic and smelly.

Check regularly:

• If dry: add water or moist greens
  
• If too wet: add dry browns (e.g. straw or newspaper)

Bonus Tips for Even Faster Composting:

• Add worms: Red wigglers (Eisenia fetida) are composting champions. They consume food scraps and accelerate breakdown.
• Use a compost activator: Manure, seaweed, comfrey leaves, or commercial activators introduce beneficial bacteria and microbes.
• Harvest in stages: Even if some materials haven’t fully broken down, sift out the fine compost using a mesh screen and return the rest to the pile.
• Location matters: Place your compost pile in partial sun to retain warmth and encourage microbial activity.
• Remember speedy composting is all about balance, effort, and consistency. With just a few smart changes and a little attention, you can go from food scraps to fertile soil in weeks, not months.

Frequently Asked Questions (FAQs)

Q: What’s the fastest way to make compost?
A: Shredding materials, maintaining a balanced carbon-to-nitrogen ratio, turning regularly, and keeping moisture in check can produce compost in as little as 3–6 weeks.

Q: Can I compost without turning the pile?
A: Yes, but it will take much longer. Turning adds oxygen, which speeds up microbial activity.

Q: Is manure safe in compost?
A: Yes, well-aged manure is a great nitrogen source. Avoid fresh manure from meat-eating animals due to potential pathogens.

Q: What shouldn’t go in fast compost?
A: Avoid meat, dairy, oily food scraps, and pet waste. These attract pests and slow down decomposition.

Need Help Getting Started?

Find everything you need to speed up composting from bins and tools to organic fertiliser at Arboretum.

Shop composting tools online or visit us in-store for expert gardening advice. If you are only starting to compost read our How to Start Composting in Ireland, A Beginner’s Guide for All Seasons (link)