Should waste be chopped or shredded for optimal composting?
This is not strictly necessary, but experience shows that reducing waste size contributes to a faster composting process and ensures a more consistent, finer texture in the end product.
Why should you chop/shred waste?
- Increased surface area: Bacteria feed on the exterior of your waste. When you reduce the size of your waste, you increase the surface area available to the waste. The more surface area to attack, the faster the decomposition process proceeds. While calculations vary, you can consider every shredding action as a doubling of the surface area, resulting in a doubling of the rate of temperature rise.
-
Breaks through protective layers: Chopping your waste into small pieces cuts through the outer protective layers, such as bark, shells, peels, and skin. These layers are designed to be more resistant to bacterial attack, but by cutting through them, bacteria can more easily access the fleshy material inside. This in turn contributes to faster heating and an acceleration of the decomposition process.
- Reducing the size of your waste helps achieve a finer and more consistent texture in the final product.
Tools and techniques
|
Tool |
Pros |
Cons |
|
Knife/scissors |
Ideal for kitchen waste. Cheap and easy. |
Takes a bit longer than adding whole scraps, but the benefits are worth the effort. |
|
Pruning shears |
Ideal for thin, woody material like dead flowers and prunings. |
Not suitable for thicker scraps - though try not to add anything thicker than a finger's width. |
|
Shredder (not necessary) |
Good for large quantities. |
Can be expensive and take up a lot of storage space. |
|
Hedge trimmer |
Pile up prunings and cut through the pile. |
Quickly turns a large pile of branches into a small pile of leaves and clippings. |
|
Rotary lawnmower |
Ideal for autumn leaves. Can shred and collect at the same time. |
Also works for other non-woody garden waste. |
Chopping advice for tougher material
- Chop as much material as you can.
- Broccoli stalks and large scraps: halve or quarter them so bacteria can reach the soft inside.
- Rose stems (small diameter, less than 0.5 cm): preferably chopped into short pieces.
- Bones: chop (chicken) bones in half so bacteria can reach the inside more easily.
- Woody stems (diameter smaller than 1 cm): chop into pieces of approx. 4 cm.
- Woody stems (diameter larger than 1 cm): if possible, put through a shredder.
- Tree branches: an excellent alternative to wood chips. These must truly be shredded to compost.
Tip: the more you reduce the size, the faster it composts.
Still unsure if you are making your waste small enough? Then watch our YouTube video for further explanation.
