Dealing with Slugs Without Harming Garden Wildlife

Why the Pellet Tin Is Rarely the Answer

The blue pellets we all grew up with are, thankfully, mostly gone. Metaldehyde was withdrawn from outdoor garden use across the UK in 2022, and that is good news for every frog, hedgehog, thrush and ground beetle on your patch. Metaldehyde is lethal to pets and birds, and it poisons the very creatures that would be eating your slugs for free.

The iron-phosphate pellets that remain on sale are gentler, but they are not harmless. They work by damaging the slug's gut and the dying creatures are then easy pickings for hedgehogs and birds, passing the chemical along the food chain. They also affect earthworms, and earthworms are the foundation of a healthy soil. If you have pets that hoover up anything on the lawn, or you are simply trying to build a wildlife-friendly plot, pellets are the wrong tool.

The good news is that everything below works better, costs less and leaves the garden richer.

Encourage the Slug Squad

Nature already has a slug control department. Your job is to give it somewhere to live and somewhere to hide.

• Ground beetles are the unsung heroes. A single one can eat dozens of slug eggs and small slugs in a night. They need cover to hunt from — a log pile in a shady corner, a heap of leaf litter left over winter, or a couple of old paving slabs stacked loosely.
• Frogs, toads and newts will move in if you give them a damp, sheltered spot. Even a sunken washing-up bowl with a few stones and a clump of native pondweed will do. Toads especially are slug-munching machines and will live happily in a cool border.
• Hedgehogs need a way in. Cut a 13cm square gap in the base of your fence — the standard "hedgehog highway" — and they will commute between gardens nightly. Put out a shallow dish of water, never bread or milk.
• Slow worms adore a compost heap or a sheet of corrugated metal laid on the soil, where they can bask and hunt.
• Thrushes, blackbirds, robins and song thrushes will beat you to the slugs at dawn if you leave a little untidied leaf litter and don't strim at ground level in the evening.

A "wild corner" of long grass, a nettle patch or a small log pile behind the shed is doing far more for your slug problem than any spray. Resist the urge to tidy it up.

Barriers and Defences That Genuinely Work

Barriers are at their best around containers, raised beds and newly planted seedlings — exactly the spots where damage hurts most.

• Copper tape on pot rims and raised-bed edges really does deter slugs, giving them a mild electric shock. The trick is to keep it clean and to trim back any leaf or stem that bridges it, otherwise the slugs simply walk across the bridge.
• Copper mesh stapled to the top rail of a raised bed lasts far longer than tape and looks neat.
• Wool pellets, sharp grit and crushed eggshells work reasonably on dry soil, but they lose their edge after rain. Wool pellets are the best of the three and also feed the soil as they break down.
• Raise your pots onto feet and remove the saucers. Slugs hide under damp saucers during the day and use them as a base for night raids.
• Plastic bottle cloches — a cut-down bottle with the lid off — protect tender seedlings for their first few weeks, which is when they are most vulnerable.
• Nematodes watered onto moist soil in spring or autumn, when the soil is above 5°C, will kill slugs underground. They are a biological control rather than a chemical, but be aware they affect snails too, so use them only where you really need them.

Whatever you choose, remember slugs find their way in through the tiniest gap. Check the rim of every bed and container and clear any soil bridge.

The Night Patrol

An hour after dusk, particularly after rain, take a torch out and have a look. You will be astonished how many slugs you find on a warm damp evening. This is the single most effective method there is, and it costs nothing.

Pick them into a lidded bucket, then either relocate them to a hedge bottom well away from your veg patch, or pop them in the freezer for a few hours for a humane end. Ground beetles and frogs will tidy up the rest if you simply drop them on the lawn.

While you are out there, hunt the eggs too — clusters of clear jelly, often in the soil, under pots, in crevices and beneath mulch. Squashing those is worth twenty slugs tomorrow. Skip beer traps: they drown ground beetles, which are on your side.

Gardening Habits That Cut Damage Down

• Water in the morning, not the evening. A dry soil surface by nightfall means far less slug traffic.
• Plant out sturdy, well-grown seedlings rather than soft, leggy ones. A strong plant shrugs off a nibble.
• Thin out crowded sowings. Weak, crowded growth is a slug magnet.
• Mulch more thinly. A thick, wet layer is a five-star slug hotel; a light layer feeds the soil without sheltering them.
• Grow plants slugs dislike — ferns, lavender, rosemary, hardy geraniums, sedums and anything with hairy or aromatic leaves — and save your hostas for pots with copper tape.
• Accept a few holes. A garden with slugs in it is a garden with frogs, beetles and blackbirds in it, and that is the whole point. Feed your soil well, keep plants healthy, and a bit of nibbling becomes a small price for a plot that is properly alive.