Compost in Winter 

In the cool winter conditions, the compost pile may cool and the breakdown processes will slow and may even halt. There are some things you can do to help keep your compost cosy this winter so that it continues to break down organic waste.

Compost piles are wonderful things. Composting is a biological process that decomposes organic material under aerobic (with oxygen) conditions. Composting speeds up the natural decomposition, providing optimum conditions for fungi, bacteria and invertebrates such as worms so that organic matter is broken down more quickly.

Compost is made from decomposed grass clippings, vegetable peel, leaves, small twigs, and other vegetable matter. Over time it should become a dark, crumbly mixture of organic matter, ideal for adding to your garden soil.

You may have noticed that the middle of your compost pile becomes warm through the activity of the organisms. Sometimes you may even see steam coming off the compost. This warmth allows the living organisms to work harder and break down the organic matter faster. It also helps kill weed seeds.

In the cool winter conditions, the compost pile my cool and the breakdown processes will slow and may even halt if the centre of the pile gets cold.

There are some things you can do to help keep your compost cosy this winter so that it continues to break down organic waste:

• Make a bigger compost pile.
  A bigger compost pile will hold heat more efficiently. Minimum size for a good compost pile is 1 cubic metre (1 m x 1m x 1m).
• Insulate your compost pile.
  Build a structure to contain your compost; perhaps using hollow building blocks that have good insulation properties. Alternatively, you can bury your compost pile. Dig a trench in the garden or flowerbed and add organic waste like kitchen scraps (Do not add meat, grease or animal fat!) little by little, making sure to bury the waste after each addition.
• Aeration.
  The composting process requires oxygen. Stir the pile up once a week with to prevent your organics from breaking down without oxygen. Compost needs moisture but not too much; if it gets too wet it will be cooled and a water-logged compost heap may not get enough oxygen and become anaerobic (lacking in oxygen). An anaerobic compost heap will smell bad and not be suitable for use in your garden.  
• Cover your compost pile.
  If your compost is covered, you can control the moisture so add a lid or cover with a tarpaulin. An old rug or blanket under the cover will help the insulation.
  Your compost pile should feel like a rung-out sponge. If it feels dry, wet it a little with a hose or watering can before covering again.
• Chop the material.
  Chopping the material you add to the pile into small pieces less than 5 cm in size will allow the pile to heat more evenly and will insulate it from the external cold.

Follow these simple guidelines and you can keep your compost pile composting through the cold months.

• See How to Make the Best Compost

David Brittain
Kiwicare