Compost Troubleshooting
Technique
Most compost problems are simply signs that the balance of air, moisture and materials needs adjusting. A healthy heap smells earthy, feels damp like a wrung-out sponge and slowly shrinks. Checking it occasionally helps you correct a problem early, rather than abandoning a bin that only needs a little attention.
How it works
A smelly, slimy heap is usually too wet or too rich in greens, leaving microbes short of oxygen. Fork it open, add shredded browns and turn. A dry heap that barely changes has too many browns or too little moisture: add water and some greens. If a heap will not heat, it may be too small, too dry, poorly mixed or short of nitrogen. Grass clumps need breaking apart, while matted leaves benefit from mixing. Flies and vermin are usually prevented by covering fresh scraps and excluding unsuitable food and pet waste.
Details
Do not expect a cold compost bin to heat like a hot heap; slow progress can be normal in winter. If rodents are present, stop adding meat, fish, dairy, cooked food and dog or cat waste, and make sure kitchen scraps are covered with browns. Some council garden-waste collections accept materials that should not enter a home heap. Soggy contents may need temporary shelter from rain, whereas a dusty pile benefits from water from a water butt. Weed seeds or diseased pieces in finished compost indicate that the heap did not become hot enough, so use that compost beneath mulch or on non-sensitive areas.
Tips
Keep a simple reserve of dry leaves, straw or torn cardboard for quick corrections. Turn only as much as you can manage: one thorough turn often solves more than frequent poking. If vegetables show distorted growth after compost use, stop using it and consider whether manure, hay or grass containing aminopyralid residues entered the heap.
Compost Troubleshooting: frequently asked questions
How does compost troubleshooting work?
A smelly, slimy heap is usually too wet or too rich in greens, leaving microbes short of oxygen.
What do I need to know about compost troubleshooting?
Do not expect a cold compost bin to heat like a hot heap; slow progress can be normal in winter.
What are some tips for compost troubleshooting?
Keep a simple reserve of dry leaves, straw or torn cardboard for quick corrections.
General guidance for UK gardens and allotments. Page updated 19 Sep 2026.