A compost heap is a habitat for decomposers: bacteria, fungi and other organisms break down suitable organic material. Your job is to provide conditions in which that process can work.

Composting is managed decay. Ingredients, moisture, air, particle size and temperature affect its progress. The result is a soil improver, not automatically a complete potting mix or a tested fertiliser.

Start with known, suitable material and a manageable setup. Follow the safety lesson for lifting, tools, dust and hygiene. Good appearance or an earthy smell can help judge maturity, but cannot establish that a batch is free of pathogens, viable weeds or chemical contamination.