Expert interview: «And then the slugs exploded»
21.6.2026
Translation: Katherine Martin
What’s a guilt-free way of banishing slugs from a vegetable patch? When I take this question to retired biologist Bernhard Speiser, his advice makes me soften up towards my garden’s slimy inhabitants.
I recently wrote an article about my attempts to get rid of the slugs in my vegetable patch. During my search for the ultimate anti-slug remedy – one that was ethical and environmentally friendly – I came across the biologist Bernhard Speiser. In his years-long stint at the Research Institute of Organic Agriculture (FiBL), it was up to him to find ways of curbing slugs on organic vegetable farms and sharing that knowledge with amateur gardeners too.
Today, the slug expert is retired and a proponent of taking a gentle approach to these slimy little garden dwellers. When I talked to him, he showed me a new way of looking at my slug problem. My main takeaway? There’s no such thing as a perfect anti-slug solution – and wherever there’s nature, slugs have a right to be there.
Mr Speiser, how can I get rid of the slugs in my vegetable patch?
Bernhard Speiser: I’ve been asked this question loads of times. And it’s no coincidence that you’re asking. As soon as we get a spell of wet weather, people go looking for advice from «the slug expert» – it’s the same every year. I’ve been giving advice on this for years, but now that I’m retired and have a bit more perspective, I’ve found myself thinking, «Hang on, is it really necessary to wipe out every last slug in your garden?» Don’t get me wrong, I understand where you’re coming from. I have a garden too, and it’s frustrating when you plant seedlings, only to find the next morning that they’re all gone.
Source: Bernhard Speiser
There’s something cruel about anti-slug remedies. I actually tried freezing them once, because I read that it was the most humane method. I felt like a murderer on an episode of CSI.
I can imagine. That method is one of the gentler ones, though. When temperatures drop, slugs slow down their metabolism and go into hibernation. Pouring boiling water over them is probably more brutal. Someone once told me that she didn’t know what to do with all the slugs she’d gathered up, so she put them in the microwave.
Oh ...
She said, «And then the slugs exploded.» She was so repulsed by it that she bought a new microwave. Maybe that was her cosmic retribution for the cruelty.
What do you think about cutting slugs in half?
A long time ago, I was helping out on an organic farm and had to spend an afternoon cutting up slugs. With every hour that passed, I became more and more averse to it. Yes, it’s a non-toxic method, but it’s certainly not nice.
In your opinion, is there a humane way to kill slugs?
No, there’s no method I can recommend in good conscience. Although we can’t tell how slugs feel or even whether they feel at all, common sense tells me that they don’t like dying either.
«In my view, they’re highly evolved animals. Sometimes they exhibit really interesting behaviour, for instance when choosing food.»
I’d originally hoped a slug fence would keep slugs out of my vegetable patch, but they’re still getting in and eating my seedlings. Are people wrong to think slug fences are of any use?
Slug fences are really useful because they keep out most slugs – perhaps 80 to 90 per cent. The thing people are wrong about is thinking that a fence provides 100 per cent protection. By the way, those little, round snail collars you can get have a similar effect and are easier to set up. I think both are great when combined with a relatively small amount of organic slug pellets. But only use them sparingly, and only sprinkle them inside of the collar. To protect harmless snails, you should never spread slug pellets across the entire garden.
**I scattered organic slug pellets inside my slug fence too, but I’m still finding slug trails.****
Slug pellets are approved plant protection products, so they’ve passed the efficacy test. Even so, it’d be asking a lot if they had to prevent every single slug trail. In the end, every method is relative. They improve the problem, but don’t always get a perfect result.
How do you put that knowledge into practice?
I have numerous plants in my garden that are naturally resistant to slugs. There are plenty of them, so it makes gardening a hassle-free experience.
Hassle-free sounds good. Does that include edible plants as well?
I have to admit, it’s mostly flowers. But currants, lamb’s lettuce and tomatoes aren’t vulnerable to slugs either – and fruit trees certainly aren’t.
Would you recommend gardeners stick to slug-resistant plants?
I don’t want to dictate what people should or shouldn’t plant. However, I do generally recommend focusing on plants that are less susceptible to slug attacks. I sometimes get the impression that people plant vulnerable plants without really thinking about it, then spend the whole summer trying to keep slugs at bay.
What if I really wanted to grow strawberries in my garden?
If that’s something you feel a real desire to do, then go ahead. Just be aware that you’ll probably have a slug battle on your hands. If you’re not comfortable with that, you’d be better off buying strawberries and planting something tougher in your vegetable patch.
Source: Ann-Kathrin Schäfer
Would a raised bed get rid of the slug problem once and for all?
A raised bed? Just because of slugs? Put it this way, if you want a raised bed as a design element, you should install one – and it might minimise your slug problem. But would you really want to put something that attention-grabbing in your garden, purely because of some slugs? If you ask me, the benefit wouldn’t justify the effort.
Home remedies such as sawdust, coffee grounds, eggshells and plant extracts supposedly help with slugs. In your experience, do any of these things actually work?
In the 1990s and early 2000s, I did a lot of research into alternative garden pest control methods. However, we didn’t find anything that worked reliably. Take sawdust, for example. Since slugs like moisture, they avoid dry sawdust. But when it rains, sawdust gets wet too. It’s a pseudo-solution that only works in dry conditions i.e. when slugs aren’t that big a problem to begin with.
In your former job, you spent many years figuring out how to control slugs in organic vegetable farming. What can amateur gardeners learn from agriculture?
Not much, because the conditions are different. In agriculture, it helps that large areas of land are involved. If the first two metres of a field are infested with slugs, there’s still plenty of field left. In a regular garden, those same two metres take up almost the whole vegetable patch.
What do you do if you find a slug in your garden?
If I happen to spot a slug on a vulnerable plant, I throw it on the compost pile. There, they do more good than harm. Gardens can accommodate a serious number of slugs, which are good at hiding during the day. To find them all, I’d need to spend hours collecting them. That would take the joy out of gardening for me, which would be a shame, considering how much of a gift it is to have a garden.
A much-touted piece of advice is to design your garden to be as natural as possible so that it attracts natural slug predators such as hedgehogs and ground beetles. What does your garden look like?
My garden is varied and designed to be close to nature because that’s my idea of an attractive organic garden. Keeping slugs at bay isn’t my number-one priority – in fact, the wide mix of vegetation in my garden provides shelter for slugs. The only real way to get rid of slugs would be to pour concrete onto the garden and pop down a few flower pots. But that’d be a pretty joyless solution.
Okay, maybe I’d rather have slugs in my garden after all …
At the end of the day, nature isn’t just there to serve us humans. There’s a hedgehog that visits our garden regularly, but I don’t imagine that it eats all the slugs. Even so, it makes me happy every time I hear it rustling around.
Are your garden slugs starting to grow on you? Or do you have a secret anti-slug remedy? Let me know in the comments.
Header image: Ann-Kathrin Schäfer
Ann-Kathrin Schäfer
Editor freelance
simon.balissat@digitecgalaxus.chI'm really a journalist, but in recent years I've also been working more and more as a pound cake baker, family dog trainer and expert on diggers. My heart melts when I see my children laugh with tears of joy as they fall asleep blissfully next to each other in the evening. They give me inspiration to write every day - they've also shown me the difference between a wheel loader, an asphalt paver and a bulldozer.
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