Pest and Disease Spotlight – Slugs and Snails
May 30, 2023

Slugs and snails are very closely related, so close in fact that a snail is just a slug with a hard shell. The group they belong to is so diverse that it also includes squid and octopus. And to complete the picture, apart from a book on biology, the only time you might find them all together in one place is a French menu, which is where we might prefer them to be. Mind you, in fairness to the French, and while we have eaten in France, we can’t remember slugs being a choice, even with garlic, but you never know.

These pests hold a unique position in the garden list of undesirables because they are a permanent fixture no matter what time of year. They are a problem in every garden in the country. Here’s a question for you – if you have snails, what does that tell you about your soil?

On the face of it, these invertebrates should be limited in how far they can spread in the garden because they can easily dry out if they’re not careful but also, they don’t exactly race about in the border. Despite that, The Royal Horticultural Society rates them as one of the most serious pests in anybody’s garden, and one which cannot be eradicated.

Whether it’s a slug or a snail, the damage they cause is the same because  the way they feed. In their mouth is a flexible file with scores of sharp teeth on it and they use it to rasp away at whatever they want to eat. Their diet isn’t confined to leaves, they will gnaw away at flowers, stems, bulbs and even tubers like Dahlia and potato.

These pests will cause damage all year round, especially slugs, but they will cause the most damage to new growth or young plants when the weather is warm, humid and especially at night. One of several possible remedies is, after it has been raining in the summer, go out after dark with a flashlight, pick them up and put them in a bucket. The book that tip came from didn’t give any advice about what you do when the bucket gets full. One possible option is a French cookbook.

So if we can’t eliminate them and we don’t want to listen to our garden being slowly eaten to death on a warm summer evening, what are we supposed to do?

Bearing in mind that the more mature the garden, the less obvious is the damage. The easiest thing to start with is to decide whether you want to just put up with them, some gardeners do and that’s fine. The next easiest would be to look at what they do and do not like to eat. Their favourite food is Hostas, whilst their least favourite would be something like bamboo, or plants with a lot of silica in them. The Royal Horticultural Society has a list of plants that seem to resist being eaten.

Some things you can do involve eggshells, sheep’s wool, copper strips, coffee grounds and beer traps. The first four in this group interfere with how slugs and snails move. Drowning in Budweiser is guaranteed to interfere with anything getting about. Try these things by all means but we can’t recall seeing bags of sheep’s wool in a garden centre. For us, those kinds of things belong in the same very admiral category as cutting your own hair and making your own clothes- all likely to be low cost but with an unpredictable outcome.

There are biological control methods which use live nematodes. They do work but only at their best when the temperature is above a certain level.

Slug pellets are available which now contain the much safer ferric phosphate, metaldehyde having been withdrawn. They do work and we are much happier to use them than we used to be.

The Royal Horticultural Society’s website has lots of useful information about slugs and snails, including control methods and a useful list of plants which are less susceptible to being eaten.

This is a pest which can be kept under control but we gardeners will need to use more than one way to do this, including the philosophical approach, meaning, if molluscs munch by moonlight just mellow with Medoc or Moet.