Compost Heap: What It Is, How to Build One, and How to Use It Properly
A compost heap is one of the simplest, cheapest, and most effective ways to turn garden and kitchen waste into rich, natural compost. Unlike compost bins, a compost heap is open and flexible, making it ideal for gardeners, allotment holders, and anyone producing larger amounts of green waste.
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This guide explains what a compost heap is, how to build one, what to put in it, how to maintain it, and how to get the best compost from it.
What Is a Compost Heap?
A compost heap is a pile of organic material left to break down naturally through decomposition. Microorganisms, worms, insects, air, and moisture work together to turn waste into compost over time.
Compost heaps:
- Are usually open or lightly contained
- Handle large volumes of waste
- Cost little or nothing to set up
- Produce excellent compost for gardens and allotments
They are especially popular on allotments where space is less limited.
Compost Heap vs Compost Bin
While both do the same job, there are some differences:
Compost Heap
- Open system
- Easy to add large waste
- Faster breakdown when turned
- Requires more space
Compost Bin
- Enclosed system
- Neater appearance
- Better heat retention
- More pest-resistant
Many gardeners use both, with a heap for bulk waste and a bin for finer materials.
Where to Put a Compost Heap
Choose a spot that is:
- On bare soil (not concrete)
- Well-drained
- Partly sunny
- Easy to access year-round
Contact with soil allows worms and beneficial organisms to enter the heap and speed up decomposition.
How to Build a Compost Heap
You can keep a compost heap completely open or lightly contained.
Simple Open Heap
- Just pile compostable material directly on the ground
- Best for large gardens or allotments
Contained Heap
- Use pallets, timber boards, or wire mesh
- Helps keep the heap tidy
- Makes turning easier
A typical compost heap should be at least 1m x 1m x 1m to retain enough heat for effective composting.
What to Put on a Compost Heap
Successful composting relies on a balance of materials.
Green Materials (Nitrogen-Rich)
- Fruit and vegetable peelings
- Grass clippings
- Fresh weeds (without seeds)
- Plant trimmings
- Coffee grounds and tea bags
Brown Materials (Carbon-Rich)
- Cardboard and paper (torn up)
- Dry leaves
- Straw or hay
- Egg boxes
- Wood chips (small amounts)
Aim for roughly equal amounts of greens and browns.
What Not to Put on a Compost Heap
Avoid adding:
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- Meat or fish
- Dairy products
- Cooked food
- Oils and fats
- Diseased plants
- Pet waste
These can cause smells, attract pests, or spread disease.
How to Layer a Compost Heap
- Start with coarse material (twigs or straw) for airflow
- Add alternating layers of greens and browns
- Chop large items to speed up breakdown
- Keep the heap moist, like a damp sponge
- Cover exposed food waste with brown material
Layering helps maintain airflow and speeds composting.
Turning a Compost Heap
Turning introduces oxygen, which speeds decomposition.
- Turn every 2–4 weeks for faster compost
- Use a garden fork
- Move outer material to the centre
Turning is not essential, but it can halve composting time.
How Long Does a Compost Heap Take?
- Actively managed heap: 3–6 months
- Untouched heap: 9–12 months or longer
Finished compost should be:
- Dark brown or black
- Crumbly and soil-like
- Earthy smelling
- Free from recognisable waste
Common Compost Heap Problems
Bad smells
Usually caused by too much green waste or excess moisture — add browns and turn the heap.
Slow breakdown
Often due to dryness or lack of nitrogen — add greens and water lightly.
Flies
Food waste exposed — cover with cardboard or straw.
Rats
Avoid cooked food and meat; keep waste buried in the heap.
Using Finished Compost
Compost from a heap can be used to:
- Improve garden soil
- Mulch beds and borders
- Boost vegetable plots
- Improve soil structure
- Feed trees and shrubs
It works best mixed into soil or used as a surface mulch.
Making Multiple Compost Heaps
Many experienced gardeners use three heaps:
- Fresh waste heap
- Actively composting heap
- Finished compost heap
This system keeps compost flowing and makes management easier.
Is a Compost Heap Worth It?
Absolutely. Compost heaps:
- Handle large volumes of waste
- Cost very little to create
- Produce excellent compost
- Reduce garden and kitchen waste
They are one of the most effective composting systems for serious gardeners.
Final Thoughts
A compost heap is a powerful, low-cost way to recycle organic waste and improve soil naturally. With the right balance of materials, occasional turning, and a bit of patience, a compost heap will reward you with rich, free compost that benefits every part of the garden.
For allotments, large gardens, or anyone serious about soil health, a compost heap is hard to beat.