Why Autumn Matters More Than You Might Think

By September, hedgehogs are in a race. Adults that bred late may still be feeding young, while this year's hoglets — often born as late as August or September — have only a few weeks to put on enough weight to see them through winter. A hedgehog needs to reach roughly 450 to 600 grams before hibernation, and anything lighter may not survive the cold. Everything you do in the garden between now and the first hard frost can tip the balance.

The good news is that helping them takes very little effort, and most of it involves doing less rather than more. A tidy autumn garden is a hostile one. Leave the leaves, leave the logs, and leave the edges a bit rough.

Build a Log Pile They Will Actually Use

Hedgehogs do not dig burrows for hibernation. They look for dry, sheltered, well-insulated spots — and a loosely stacked pile of logs and leaves is close to ideal. Build one in a quiet corner, ideally against a wall, fence or hedge, and facing south or west so it catches a little warmth.

• Use untreated hardwood where you can, with the bark left on. Avoid freshly treated timber.
• Stack loosely rather than tightly, leaving gaps of 10 to 15 centimetres for a hedgehog to squeeze into.
• Add a base layer of dry leaves, twigs and a little moss. This is what actually keeps them warm.
• Keep it dry. A sheet of roofing felt or a couple of overlapping boards on top is fine, provided it doesn't seal the pile shut.

Then leave it alone. A log pile that gets moved, turned or burned in November is worse than no log pile at all. If you'd rather something more deliberate, a purpose-built hedgehog house — a wooden box with a tunnel entrance, filled with dry leaves — works well, but site it before the end of October so there is time for it to be found.

Compost heaps, leaf mould piles and dense ground cover all do the same job. So does simply leaving a corner of the lawn unmown through autumn.

Food and Water

A hedgehog's natural diet is beetles, caterpillars, earthworms and slugs, and a wildlife-friendly garden will supply much of it. But in autumn, when they need to gain weight quickly, supplementary food is genuinely useful.

• Meaty cat or dog food — the pâté style, not gravy or fish-based. A small dish each evening.
• Kitten biscuits or specialist hedgehog food for crunch and calcium.
• Fresh water in a shallow dish, no more than two or three centimetres deep, with a few pebbles in it so a small hedgehog can climb out.

Never put out bread and milk. It causes diarrhoea and dehydration, and it has killed a great many hedgehogs over the years. Dried mealworms are fine as an occasional treat but should not be the main offering — fed in quantity they can cause serious calcium deficiency and bone problems.

Put food out at dusk and clear anything left over in the morning to avoid attracting rats. If you have cats, feed the hedgehogs somewhere a cat can't reach, or use a feeding box with a narrow entrance.

Why Slug Pellets Cause So Much Damage

Slug pellets are one of the biggest killers of garden hedgehogs. Hedgehogs rarely eat the pellets directly — they eat the poisoned slugs and snails, and the active ingredient, metaldehyde, builds up in their system. Affected animals often appear wobbly, uncoordinated and very thirsty before dying. Metaldehyde pellets are now banned for outdoor use in the UK, but plenty of old tubs are still sitting in sheds, and they should go to the tip rather than on the border.

There are better ways to deal with slugs. Hand-pick them after rain, sink beer traps into the soil, encourage frogs and ground beetles, or use biological nematode controls, which are safe for mammals. If you must use a slug product, choose one based on ferric phosphate and use it sparingly, well away from anywhere hedgehogs forage. Better still, accept a few holes in the hostas.

Autumn Hazards Worth a Ten-Minute Check

• Bonfires. Build the pile on the day you plan to burn it, and check it thoroughly before lighting. Never light a pile that has been sitting for days.
• Strimmers and mowers. Check long grass, nettle patches and the base of hedges before you cut. Hoglets tuck themselves into exactly that sort of cover.
• Netting. Pea netting, fruit netting and football goal nets trap hedgehogs by the spines. Keep it 30 centimetres off the ground or pack it away.
• Ponds. Hedgehogs swim well but cannot climb out of steep-sided water. Add a gently sloping stone ramp or a shallow shelf at one edge.
• Drains and holes. Cover any open drain, light well or gap under a shed that a hedgehog could tumble into.

When to Step In

Most hedgehogs will manage perfectly well without you. But there are times when intervention is the right call. A hedgehog out in daylight in autumn is usually in trouble. So is one that looks unsteady, is clearly underweight, or is still wandering about after the first hard frosts. Anything under about 450 grams in late October or November is unlikely to make it through hibernation.

If you find one, put it in a high-sided box lined with an old towel, keep it somewhere cool and quiet, and offer shallow water and a little meaty cat food. Don't try to warm it up quickly and don't attempt to keep it as a pet. Ring your local hedgehog rescue or wildlife hospital for advice — they will tell you whether it needs to come in for the winter. Then, when spring arrives and the ground softens, you can put that log pile to use all over again.