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Why a tidy corner beats a tidy garden

Every autumn, gardens across the country get stripped bare. Beds are cleared, borders are cut back, and the resulting mountain of twigs, leaves and clippings is bagged up and carted off to the tip. It looks neat. It also removes one of the most valuable things you can offer wildlife: a habitat pile.

A habitat pile is exactly what it sounds like — an untidy heap of natural material left to rot down slowly in a quiet corner. It costs nothing, takes twenty minutes to build, and provides shelter for everything from hedgehogs and slow worms to solitary bees, beetles and the caterpillars of overwintering moths. The trick is not to clear everything away, but to tidy with a purpose and leave the spoils somewhere useful.

If you garden on sandy, acidic soil, you are already halfway to mimicking one of our rarest habitats. Britain holds around a fifth of the world's lowland heathland, and the wildlife that depends on it — nightjars, silver-studded blue butterflies, sand lizards — has been squeezed into ever smaller fragments. Garden piles of brash, deadwood and leaf litter copy the structure of a heath edge remarkably well.

What makes a good habitat pile

The best piles are loose, mixed and damp-ish at the base. Dense, compacted heaps rot anaerobically and turn into slime, which supports very little. Aim for air gaps, a variety of material sizes, and contact with bare soil so invertebrates can burrow in from below.

A few principles worth following:

• Mix your materials. Twigs and prunings provide structure; leaves and soft clippings fill the gaps and hold moisture.
• Keep it loose. Drop material in rather than pressing it down. A pile you could push a hand into is about right.
• Include some thicker wood. Logs and branches rot slowly and stay useful for years, unlike a heap of grass.
• Avoid treated timber, painted wood, and anything sprayed with weedkiller. Fresh lawn clippings should go in thin layers, never in a thick, airless mound.
• Site it on soil, not paving. Bare ground underneath lets beetles, frogs and small mammals get in.

Three piles worth building

You do not need a large garden to do this. A single pile in a metre-wide corner will do, or you can build several small ones with different characters.

• A twig and brash pile. The classic hedgehog hibernation site. Build it from hedge trimmings, buddleia prunings, dead stems and a few thicker branches. Hedgehogs need a dry, undisturbed core, so leave the middle alone and add to the outside. Position it against a fence or hedge, out of prevailing wind, and cover the top loosely with leaves or a sheet of bark. Do not put it on top of a waterproof membrane — the base needs to drain.
• A leaf pile or leaf mould corner. Oak, beech and birch leaves break down slowly and make superb leaf mould after a year or two. Rake them into a wire cage or just heap them behind a shrub. Frogs, newts, toads and hibernating queen bumblebees all use leaf litter. Robins and blackbirds will work through it for grubs all winter.
• A loggery or deadwood stack. Stack cut logs with the sawn ends facing outwards, part-buried at the base if you can manage it. This is the single best thing you can do for stag beetles, whose larvae need rotting wood underground, and for lesser stag beetles, centipedes and woodlice. Include some upright stumps too — solitary bees will nest in the old beetle holes.

Heathland lessons for the garden

Heathland managers work with exactly these structures. When gorse and birch scrub is cut back to protect heather, the cut material is often left in loose brash piles at the edge of the open ground rather than burned. Those piles warm up quickly in sun, provide basking spots for common lizards and adders, and shelter invertebrate prey.

You can copy that in miniature. If you grow heather, gorse or broom on acidic soil, cut it in late winter or early spring and stack the brash in a sunny spot near the planting. Add heath bedstraw, tormentil, sheep's sorrel or bilberry around the edges if your soil allows, and keep a patch of bare, sandy ground open beside the pile. Bare ground is the unsung hero of heathland conservation — many solitary bees and wasps nest in it, and the warmth helps them get going in the morning.

If your garden is neutral or alkaline, do not worry. Habitat piles work everywhere. You will simply attract a different, equally valuable cast of species.

Where to put it, and what to avoid

Choose somewhere out of the way of your main routes: behind a shed, at the end of a border, under a mature shrub, or in the strip beyond the lawn. You want a spot you will not need to move for at least two or three years, because disturbance is the main thing that ruins a pile.

Things to steer clear of:

• Do not pile material against your house wall or a wooden shed. Damp heaps can encourage fungal decay in timber.
• Avoid anywhere that floods badly. Waterlogged, stagnant piles go sour.
• Do not use clippings from invasive plants. Bramble fragments, Japanese knotweed and couch grass roots will happily regrow.
• Keep piles away from where you might use a strimmer or mower regularly. Hedgehogs and frogs sit tight rather than flee.

Looking after it through the year

A habitat pile is low maintenance, but not no maintenance. Add prunings as you go, a little at a time — thin layers rot better than sudden dumps. When the heap settles and shrinks in summer, top it up. If it becomes compacted, fork it gently at the edges and scatter some of the older, crumbly material around the garden as a mulch.

The one golden rule is timing. In the UK, hedge and shrub cutting should avoid the main nesting season between March and August. Doing your structural pruning in late winter, or a light trim in early autumn, keeps you clear of birds on nests and gives hibernating animals time to settle before the cold.

Leave the pile alone from October through to April, and resist the urge to tidy it in spring. A heap that looks like a mess to you is a hibernaculum, a nursery and a larder to everything else. Build one this year, in the quietest corner you have, and let it rot quietly in its own time.