Composting is one of the best things you can do for your garden — it turns kitchen and garden waste into rich, dark, crumbly soil improver that plants love. And the cheapest way to get started is to build a compost bin from free pallets. The slatted design provides the airflow that composting needs, and the whole thing takes about an hour to build.
Why Build Rather Than Buy?
- Free or near-free (pallets are widely available at no cost)
- Larger capacity than most shop-bought bins — more compost, faster
- Better airflow than enclosed plastic bins — the gaps between pallet slats are perfect for composting
- Easy to repair or replace — if a board rots, swap it out
- Customisable — build one bay, two bays, or three for a full rotation system
Single Bay vs Multi-Bay
| Setup | Pallets Needed | Best For | Notes |
|---|---|---|---|
| Single bay | 4 | Small gardens, beginners | Fill, leave, empty when ready |
| Double bay | 6 | Medium gardens | One bay composts while you fill the other |
| Triple bay | 8 | Large gardens, serious composters | Active filling / composting / finished — continuous supply |
A double bay is the sweet spot for most gardeners. You fill one side while the other decomposes, then swap. This gives you a continuous supply of finished compost. For more background on the composting process itself, see our composting beginner’s guide.
What You’ll Need
- 4–8 standard pallets (depending on single/double/triple bay)
- 75mm exterior screws or galvanised nails
- Cordless drill/driver
- Wire (fencing wire or cable ties) — optional for reinforcement
- Cardboard or landscape fabric (for lining — optional)
Choosing Pallets
- Look for the HT stamp (heat treated) — safe for garden use
- Avoid MB stamped pallets (methyl bromide — chemically treated)
- Choose pallets in reasonable condition — avoid heavily rotten or broken ones
- Standard Euro pallets (1200×1000mm) make a good-sized bay
Step-by-Step Build (Single Bay)
Step 1: Choose the Location
Place your bin on bare soil (not concrete or paving) — this allows worms and beneficial organisms to enter from below and drainage to occur naturally. A partially shaded spot is ideal — full sun dries the compost too quickly, deep shade keeps it too cold. Position it within reasonable distance of both your kitchen and garden for convenience.
Step 2: Set Up the Back and Sides
- Stand one pallet upright as the back wall
- Stand two pallets perpendicular as side walls
- Screw the side pallets to the back pallet at the corners — use at least 3 screws per joint (top, middle, bottom)
- Check the structure is square and sturdy
Step 3: Create the Front
The front needs to be removable or have a low access point so you can turn the compost and remove the finished material from the bottom. Options:
- Full removable front — attach the fourth pallet with wire or hooks so it lifts off entirely
- Half-height front — cut a pallet in half and fix the bottom half permanently. The top is open for access
- Sliding slats — remove the boards from the front pallet and reattach them horizontally with gaps between vertical battens, creating a ‘slot-in’ system where individual boards can be removed for access
Step 4: Reinforce (Optional)
For extra stability, drive a wooden stake into the ground at each back corner and screw the pallets to the stakes. This prevents the bin from leaning or collapsing as it fills with heavy compost.
Step 5: Line the Inside (Optional)
Lining the inside with cardboard helps retain heat and moisture while the cardboard itself decomposes over time and becomes part of the compost. Some people use chicken wire or landscape fabric to prevent material falling through the gaps — useful if you’re composting a lot of fine material like grass clippings.
What to Compost
| Greens (Nitrogen-Rich) | Browns (Carbon-Rich) | Don’t Compost |
|---|---|---|
| Vegetable peelings | Cardboard (torn up) | Meat and fish |
| Fruit waste | Dry leaves | Dairy products |
| Grass clippings | Shredded paper | Cooked food |
| Coffee grounds | Straw | Dog/cat waste |
| Tea bags (check for plastic) | Small twigs | Diseased plants |
| Young weeds | Egg boxes | Perennial weed roots |
| Plant trimmings | Wood chips | Coal or charcoal ash |
The golden rule is roughly equal parts greens and browns by volume. Too many greens makes a wet, smelly, slimy mess. Too many browns makes a dry pile that barely decomposes. The RHS composting guide covers the science behind getting the balance right.
Turning and Timing
Turn the compost with a garden fork every 2–4 weeks — this introduces air, distributes moisture, and speeds decomposition. In a well-managed bin, you’ll have usable compost in 6–12 months. Without turning, expect 12–24 months. The compost is ready when it’s dark brown, crumbly, earthy-smelling, and you can no longer identify the original materials.
Common Problems
- Smells bad — too wet, too many greens, not enough air. Add browns (cardboard, dry leaves) and turn
- Not decomposing — too dry, too many browns, pile too small. Add greens, water lightly, and turn
- Rats — don’t add cooked food, meat, or dairy. A wire mesh base discourages burrowing
- Flies — cover fresh food waste with a layer of browns (cardboard, leaves) each time you add it
