Why a Heap Attracts Visitors

A compost heap is, in essence, a slow digestive system. Given the right mixture it heats up, breaks down and smells pleasantly of damp woodland floor. Given the wrong mixture it becomes a warm, sheltered larder — and rats, mice, foxes and wasps are remarkably quick to work that out.

The good news is that pest problems in home compost are almost always a symptom of imbalance or poor siting rather than bad luck. Rodents are driven by three things: food they can smell, warmth, and cover. Take away any one of those and your bin stops being attractive. Take away all three and it becomes just another piece of garden furniture.

This is not about being fussy. It is about feeding the heap what the microorganisms can actually process, and keeping anything that would smell like a takeaway out of the mix.

The Green and Brown Balance

Every compostable material is either a "green" (nitrogen-rich, wet, soft) or a "brown" (carbon-rich, dry, structural). Greens provide the fuel; browns provide the airflow and soak up moisture. Aim for roughly two to three parts browns to one part greens by volume — more browns than most beginners expect.

• Greens: vegetable peelings, fruit scraps, tea leaves, coffee grounds, grass clippings, spent houseplants, wilted cut flowers.
• Browns: dry autumn leaves, torn cardboard, newspaper, egg boxes, loo roll tubes, straw, woodchip, shredded hedge prunings.

Kitchen scraps are almost all greens, which is precisely why a bin fed only from the caddy turns slimy, sour and smelly. Keep a lidded container of dry leaves or torn cardboard beside the bin and add a generous handful over every batch of scraps. If you have no leaves, scrunched-up paper and cardboard do the same job.

What Never Goes In

Cooked food is the single biggest cause of rodent interest. Once food has been cooked, its scent carries far further and the fats and proteins break down slowly. Keep the following out of a standard cold heap:

• Cooked leftovers of any kind, including rice, pasta and bread
• Meat, fish, bones, skin and gravy
• Dairy, including cheese rinds and yoghurt remnants
• Cooking oils, fats and sauces
• Dog and cat faeces or used cat litter
• Diseased plant material and perennial weed roots such as bindweed or ground elder
• Plastic-coated tea bags — tear them open and check the mesh
• Shiny printed paper, receipts and treated or painted wood

Citrus peel, onion skins and large quantities of cooked vegetables are best kept to a minimum: they are slow to break down and can make the heap acidic. Small amounts are fine if chopped small and buried deep.

Siting and Building a Pest-Resistant Bin

Where the bin sits matters as much as what goes in it. Position it on bare soil if you can, so worms and beneficial microbes can migrate in, but lay a sheet of fine galvanised mesh under the base, turned up at the edges. This allows drainage and worm access while stopping rats tunnelling upwards.

If you must site it on paving, that is perfectly workable — rats cannot dig through slabs — but you will need to water the heap more often and add extra browns. Keep the bin at least 30cm clear of fences, sheds and dense shrubs, and never let ivy or long grass grow up around it. Clearance removes the cover rodents rely on.

Use a bin with a close-fitting lid, and weight it down with a brick if it is the light plastic dalek type. In the kitchen, keep a small lidded caddy and empty it every day or two, rinsing it weekly. A caddy of rotting peel on the worktop is more of a draw than the heap itself.

Turning, Temperature and Moisture

Turning is what separates a working heap from a pile of rubbish. It reintroduces oxygen, distributes moisture and lets you inspect what is going on.

• Summer: turn once a week with a fork or corkscrew aerator.
• Winter: turn every fortnight, or leave it alone in hard frost and accept that everything slows down.
• Every time you add scraps: dig a hole in the centre, drop them in, and cover with browns. Never leave food scraps sitting on the surface.

A healthy heap reaches 40–60°C in the core and shrinks noticeably. If it is cold and dry, add greens and water. If it is slimy, sour and warm but not hot, add browns and turn. The moisture test is simple: squeeze a handful. It should feel like a wrung-out sponge — damp, never dripping.

Chop scraps smaller than you think necessary. A potato peeling cut into pieces disappears in days; a whole one sits there for weeks, broadcasting its presence.

Seasonal Notes from the British Garden

Autumn is a gift. Rake leaves into bin bags, punch a few holes and store them behind the shed — you will have a year's supply of browns and, eventually, leaf mould. Keep a bag beside the compost bin so you never have to go looking in January.

Winter brings cold, wet conditions and hungry rodents looking for shelter. Keep the lid tight, clear snow and fallen leaves from around the base, and resist the urge to add large quantities of soggy kitchen waste. A Bokashi bin or a wormery can take up the slack indoors or in a shed, fermenting cooked food so it can be buried later.

Spring and summer reverse the problem: grass clippings arrive in glut and mat down into an airless sludge. Mix them with shredded cardboard or straw rather than layering them, and turn more often.

Above all, be patient. A well-managed heap is not sterile or sealed — it is simply unappealing. Get the balance right, bury the scraps, turn it regularly, and you will have a bin that quietly does its work and attracts nothing more demanding than a passing blackbird.