How can we control slugs and snails in our gardens? 

Whether you're a gardening beginner or expert, Irish Examiner columnist Peter Dowdall has the answer to your questions
How can we control slugs and snails in our gardens? 

Slugs can make short work of the plants in your garden but using some barrier products and slug-resistant plants will help to maintain the natural balance and reduce the potential damage. Picture: iStock

Slugs are a persistent and perennial pest in Irish gardens. The slimy molluscs leave tell-tale trails all around the garden as they make their way to feast on horticultural delights. 

They can devastate freshly planted seedlings in an entire allotment or vegetable patch in one short few hours, normally during the night when they know that we are fast asleep. I’m convinced, in my place, that they keep an eye for when I turn out the light and then in scenes reminiscent of Peter Rabbit I can imagine the slugs dancing and laughing all night in the garden until the sun rises once more and they retreat inside their shells once more. 

Like Peter Rabbit and his friends, the slugs leave the place trashed.

As always in the garden, maintaining a natural balance is key to controlling slugs and snails. Do not under any circumstances reach for any slug pellet containing methaldehyde, as this ingredient, whilst being an effective slug killer, is also toxic to birds, hedgehogs, domestic pets and even us humans. Banned for sale in many European countries including the UK, it is still readily available here in Ireland.

By using this poison, you are so severely interfering with the natural balance that you will be dealing with slug infestations for evermore. One application of methaldehyde will wipe out nearby slugs and snails but their numbers will increase much more quickly than those of their predators, meaning that they will have free rein in your garden.

Pellets that contain ferric phosphate as an active ingredient are a much better option as a slug killer as they are harmless to surrounding wildlife and domestic pets.

Slug traps are also very effective as a means of control. You can purchase them in stores or you can make your own using an empty yoghurt container or similar. Place the trap in the ground, so the top is just at soil level and fill it to about a third with beer. 

Put a top on the trap ensuring that there is a gap or holes through which the slugs can get in. They are attracted by the alcohol and once in, they cannot escape. They are not available to birds once they are trapped and thus there is no risk of contaminating the predators.

Better again, use barrier products as these will keep your plants damage-free and at the same time, by not killing the slugs and snails you are ensuring a healthy supply of food for their predators, hedgehogs and larger birds, now that balance is being restored. 

Sheep’s wool is turned into pellets and this applied to the soil surface and moistened creates a very effective barrier for the molluscs. They simply cannot traverse the wool pellets and thus, the Hostas and their other favourites can be kept completely safe. Even better news, as the pellets break down they add humus to the soil and work as a great coil conditioning additive.

Eggshells, coffee grounds, slate and coarse bark mulch can all work to a greater or lesser degree as barriers. The important thing to remember when using a barrier product is that, if you leave any gap, they will find it and once more, the Peter Rabbit style parties will begin.

I’m a lazy gardener and everything in my garden has to really fend for itself. I will give it lots of attention and the best of starts but after that, they are largely on their own. They may get the odd feed if they look hungry and if I remember to do it and they may get a mulch of Slug Gone wool pellets or other barrier products but more often than not, they won’t!

Instead, I like to try and always use the right plants in the right soil and for the relevant aspect. In other words, shade lovers get planted near trees and large shrubs and as my soil is slightly acidic, I can successfully grow some Azaleas and Camellias without reaching for sequestered iron every few weeks. I also try and use plants that slugs don’t like and this is probably the most effective way of ensuring no slug damage in the garden.

Hosta is the poster boy plants for slug damage but there are some which are resistant to slug attack. Hosta ‘Sum and Substance’ is a real stunner in any garden. Liking a somewhat shaded and moist position, it can reach 70cm and more in height with a spread of over one metre and is resistant, though not completely immune to slug attack. Plants with slightly hairy or spiny leaves seem resistant such as nepeta or catmint, achillea and alchemillea. 

Other plants, such as digitalis and alliumm contain specific compounds which will deter slugs. I have also found, over the years that succulents such as sedum, sempervivum and echeveria, don’t seem to tingle their tastebuds, though, they do seem to be a particular delicacy of vine weevil grubs. There’s that balance again.


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