Snail pellets are small bait products scattered around gardens to kill slugs and snails before they damage plants. They come in several formulations with different active ingredients, and the differences matter, especially if you have pets, children, or wildlife visiting your garden. Here’s what you need to know about how they work, which types are safer, and what alternatives exist.
Types of Snail Pellets
Three active ingredients dominate the market: metaldehyde, iron phosphate, and ferric sodium EDTA. Each kills molluscs through a different mechanism, and they carry very different risk profiles for everything else in your garden.
Metaldehyde has been the go-to slug killer for decades. It damages the cells that produce a slug’s protective mucus layer. Without that coating, the slug desperately generates replacement slime, burning through its internal water supply. The poisoned slug becomes severely dehydrated, seeks shelter, and dies within a few days. Metaldehyde pellets are effective but highly toxic to dogs, cats, birds, and hedgehogs. The UK banned metaldehyde for outdoor use in March 2022 due to unacceptable risks to wildlife, though it remains available in some other countries including the United States.
Iron phosphate pellets arrived on the market over the last decade as a safer alternative. Once the pellets absorb moisture and slugs eat them, the iron phosphate disrupts their calcium metabolism and damages digestive tissue. The slugs stop feeding and die three to six days later. Iron phosphate breaks down into iron and phosphate in the soil, both of which are naturally occurring nutrients, making these pellets a lower-risk option around pets and wildlife.
Ferric sodium EDTA is the newest option. It works similarly to iron phosphate but tends to be faster-acting. These pellets are also considered lower risk than metaldehyde, though they’re less widely available.
How to Use Snail Pellets Effectively
Pellets work best when scattered thinly and evenly around vulnerable plants rather than piled in heaps. A few pellets per square metre is typically enough. Heaping them defeats the purpose: the goal is to intercept slugs and snails as they travel toward your plants, not to create a single feeding station. Most pellets lose effectiveness after rain, so you may need to reapply after heavy downpours.
Timing matters too. Slugs and snails are most active in mild, damp conditions, particularly in spring and autumn. Applying pellets in the evening, when molluscs begin to feed, gives the bait the best chance of being found before it degrades.
Risks to Pets and Wildlife
Metaldehyde is the ingredient that causes the most serious poisoning incidents. Dogs are particularly vulnerable because many find the pellets palatable. The lethal dose varies by body weight, but even a small amount can trigger severe symptoms including muscle tremors, seizures, rapid breathing, and overheating. There is no antidote for metaldehyde poisoning. Veterinary treatment involves decontamination, intravenous fluids, liver support, and medications to control symptoms, and it can take several days. If you suspect your dog has eaten metaldehyde-based pellets, this is a genuine emergency with no time to wait.
Iron phosphate pellets are far less dangerous to pets. A dog eating a handful is unlikely to experience serious toxicity, though large quantities of any foreign substance can cause stomach upset. If you have dogs, cats, or frequent wildlife visitors like hedgehogs, iron phosphate or ferric sodium EDTA products are the safer choice by a wide margin.
The UK Metaldehyde Ban
In September 2020, the UK government announced a ban on metaldehyde following advice from the Expert Committee on Pesticides and the Health and Safety Executive about risks to birds and mammals. Supply of metaldehyde products ended on 31 March 2021, and all sale and use became illegal from 1 April 2022. This applies across all of Great Britain and to all users, including home gardeners and commercial growers. If you’re in the UK, any snail pellets you buy now will contain iron phosphate or ferric sodium EDTA.
Alternatives to Pellets
If you’d rather skip chemical controls entirely, several other approaches can help manage slugs and snails, though none is a silver bullet.
Biological control uses a microscopic nematode (sold under the name “Nemaslug”) that’s watered into the soil. The nematodes enter slugs’ bodies and infect them with bacteria that cause a fatal disease. They’re specific to molluscs and don’t harm other animals, but they need moist soil between 5 and 20°C to work, making spring through early autumn the effective window. One important limitation: nematodes live in the soil, so they’re effective against slugs but unlikely to affect snails, which spend less time in contact with the ground.
Beer traps are a classic approach. Jars part-filled with beer and sunk into the soil near vulnerable plants attract slugs, which fall in and drown. Scooped-out citrus or melon halves placed cut-side down also work as traps. Both need to be checked and emptied regularly, ideally every morning.
Barriers are popular but less reliable than many gardeners assume. A Royal Horticultural Society study tested copper tape, bark mulch, eggshells, sharp grit, and wool pellets in a realistic garden setting and found none of them reduced slug damage. Some earlier lab studies showed copper-based barriers could repel slugs, but the real-world results were disappointing. If you use barriers, treat them as one layer of defense rather than a standalone solution.
Hand-picking slugs and snails after dark, when they’re actively feeding, remains one of the most reliable non-chemical methods. It’s tedious but effective, especially when done consistently in the first few weeks of the growing season before populations build up.