Snails are often so abundant in gardens that some damage has to be tolerated. They cannot be eradicated so target control measures on protecting the more vulnerable plants, such as hostas, seedlings, vegetables and soft young shoots on herbaceous plants.
There are many preventive measures that have been used by gardeners to minimise snail damage. Most of these do not have any scientific evidence to prove that they are effective. These measures include:
- Transplanting sturdy plantlets grown on in pots, rather than young vulnerable seedlings. Transplants can be given some protection with cloches
- Torchlight searches on mild evenings, especially when the weather is damp; hand-picking snails into a container. They can then be taken to a field, hedgerow or patch of waste ground well away from gardens, or killed in the freezer before being added to the compost heap or put in the bin
- Some birds, frogs, toads, hedgehogs, slow-worms and ground beetles eat slugs and snails and these predators should be encouraged in gardens
- Raking over soil and removing fallen leaves during winter can allow birds to eat slug eggs that have been exposed
- Traps, such as scooped out half orange, grapefruit or melon skins, can be laid cut side down, or jars part-filled with beer and sunk into the soil near vulnerable plants. Check and empty these regularly, preferably every morning. Proprietary traps are also available from garden centres and mail order suppliers
- Barriers, thought to repel snails, include rough or sharp textured mulches and substances thought to be distasteful or strong smelling. Copper-base barriers have been shown to repel slugs in some studies. A recent RHS study in a garden-realistic scenario however, found no reduction in slug damage from barriers made of copper tape, bark mulch, eggshells, sharp grit or wool pellets
Most of these non-chemical control options have very little scientific research into them, but the RHS is hoping to address this knowledge gap and is carrying out a range of scientific studies.
The nematode biological control available to control slugs is unlikely to affect snails, as they rarely come into contact with the soil-dwelling nematodes.
Following the manufactures instructions scatter slug pellets thinly around vulnerable plants, such as seedlings, vegetables and young shoots on herbaceous plants. It is important store pellets safely and scatter them thinly as they can harm other wildlife, pets and young children if eaten in quantity.
Until spring 2020 there are two types of slug pellet approved for use in gardens, those based on metaldehyde and those based on ferric phosphate. Ferric phosphate based pellets are approved for use by organic growers. Products include Growing Success Advanced Slug Killer, Solabiol Garden Slug Killer, Vitax Slug Rid, Doff Super Slug Killer, Sluggo Slug & Snail Killer and SlugClear Ultra3. To protect children and pets pellets must be used as directed.
Metaldehyde ban in 2020
In December 2018 DEFRA announced that metaldehyde will be banned from most uses in Spring 2020. The ban includes all home garden use. The decision followed advice from the UK expert committee on Pesticide and the Health and Safety Executive (HSE) who considered that metaldehyde poses an unacceptable risk to birds and mammals. Until the ban comes into force products containing metaldehyde continue to be used although they may become unavailable in the supply chain. Out of date products must be disposed of responsibly advice can be found here
Products for home garden use containing metaldehyde include Ultimate Slug and Snail Killer, Deadfast Slug Killer, Doff Slug Killer Blue Mini Pellets, Westland Eraza Slug and Snail Killer.
Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener
Most plants, once established, will tolerate some snail damage and control measures can be discontinued.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)