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 various measures you can take:
- Transplant sturdy plantlets grown on in pots, rather than young vulnerable seedlings. Transplants can be given some additional protection with cloches
- Encourage predators such as thrushes, toads, hedgehogs and ground beetles. The biological control nematode (‘Nemaslug’), Phasmarhabditis hermaphrodita, is used to control slugs in the soil but is unlikely to control snails, since they spend most of their time at or above soil level
- Place traps, such as scooped-out half orange, grapefruit or melon skins, laid cut side down near vulnerable plants, or jars part-filled with beer and sunk into the soil. Check these and empty them regularly, preferably every morning. Proprietary traps and barriers are also available from garden centres and mail order suppliers
- Place barriers, such as copper tapes around pots or stand containers on matting impregnated with copper salts. Moisture-absorbent minerals can be placed around plants to create slug barriers .Gel repellents can also be used to create barriers around plants. These products are widely available from garden centres and mail order suppliers
- Go out with a torch on mild evenings, especially when the weather is damp, and hand-pick snails into a container. Then, either take them to a field, hedgerow or patch of waste ground well away from gardens, or destroy them in hot water or a strong salt solution
- Turn over likely hiding places in winter to expose snails for thrushes to feed on
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.
There are two types of pellet available to the gardener; those that contain metaldehyde (e.g. Bayer Ultimate Slug and Snail Killer, Deadfast Slug Killer, Doff Slug Killer Blue Mini Pellets, Westland Eraza Slug and Snail Killer) or ferric phosphate (e.g. Growing Success Advanced Slug Killer, Bayer Garden Slug Killer, Bayer Organic Slug Bait, Vitax Slug Rid, Doff Super Slug Killer, Sluggo Slug & Snail Killer, SlugClear Ultra3). Ferric phosphate is approved for use by organic growers and is relatively non-toxic to vertebrate animals.
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)