There's a lot of repetitive advice online about dealing with slugs. In my experience, a good chunk of it simply doesn't work and seems to be blindly regurgitated from one site to the next. What follows is what I'd actually focus on - first the habitat problems worth fixing or avoiding, then the handful of treatments I've found do something, with honest notes on where they fall short.
If you've got old carpet down in the garden - under beds, on paths, or in bunches anywhere - get rid of it. The underside stays dark and damp, which is more or less ideal slug habitat. I replaced mine with wood chip and bark.
Removing the carpet takes away the shelter, and that alone helps. I'd add a caveat, though: I reckon the bark also brought in more predators. I'm seeing more ground beetles and more centipedes - the fast, chestnut-orange ones with the long trailing back legs that give them a sort of tail. Those are the common centipede (Lithobius forficatus). Both are genuine slug predators: Oregon State University's slug portal lists centipedes and ground beetles among the invertebrates that feed on slugs and their eggs, and the Woodland Trust calls the common centipede a gardener's friend for the same reason. So I suspect the mulch is doing two jobs at once - though I'll be straight that the chain from mulch to fewer slugs is my own observation rather than something I can point to a controlled trial for. Worth flagging one easy mix-up while I'm at it: centipedes are the predators, not millipedes. Millipedes look similar but are detritivores - they eat decaying matter, not slugs - so if what you're seeing is the slower, rounder, many-legged type, that's a sign of busy soil rather than slug control.
Same principle as the carpet. If your raised beds are rotten and full of crevices, that's perfect slug habitat. Check the corners especially - I've pulled as many as five out of a single corner. Either repair the beds or replace the worst of the timber; the gaps are doing you no favours.
If you've got slugs, direct sowing their favourites - lettuce being the obvious one - is asking for trouble. The seedlings get grazed off the moment they break the surface, and because you never actually see them, it's easy to assume the seed failed to germinate. Radish and other tender seedlings go the same way. The fix is to start them somewhere out of reach - modules, a tray on a bench, a windowsill - and transplant them out once they're big enough to take a bit of damage without being killed off. By then you can keep an eye on them and deal with any slugs directly.
None of these is a silver bullet, but each one does something. Worth saying up front: everything I list here is organic. I avoid non-organic controls where I can, so the stronger synthetic stuff doesn't get a mention - that's a deliberate choice on my part rather than a claim it doesn't work.
This works, but only for a short while - it deters slugs rather than killing them, and it washes off, so you're committing to regular reapplication. To make it: take two whole bulbs of garlic, crush them and simmer in around two litres of water until soft. Squash everything down with a fork to get as much out as possible, then sieve out the skins so you're left with a cloudy concentrate. Dilute roughly two tablespoons of that into five litres of water and spray or water it over the plants and the soil around them. Reapply every week or so, and again after rain - that's the catch, miss a few wet days and the effect is gone.
I keep this as a last resort and it does seem to work. The organic question is worth getting right, since it gets repeated both ways. Sluggo is a ferric phosphate pellet, and since metaldehyde's outdoor use was banned in Britain in 2022, ferric phosphate is more or less the only slug pellet you can buy here. It's also accepted for organic growing in the UK - certified by the likes of OF&G and endorsed by Garden Organic and the Soil Association - so calling it not organic isn't right.
One thing to bear in mind with Sluggo: The manufacturer says it's harmless to earthworms, but that's disputed: these pellets rely on a chelating agent (ferric sodium EDTA) to work, and independent studies have linked that EDTA component to reduced feeding, weight loss and death in earthworms - whereas plain iron phosphate on its own didn't.
My preference is to use it sparingly and as a backup, which is what the organic bodies advise anyway.
Simple and free. Lay pieces of wood, cardboard or an upturned pot in the damp, shaded parts of the garden - or dampen the spot yourself if it's dry. Slugs shelter underneath through the day, and you just lift the trap each morning and clear off whatever has gathered. It won't clear an infestation on its own, but it chips away at the numbers and shows you where they're concentrated.
Fix the habitat first. No (organic) spray or pellet keeps up with a garden that's handing slugs somewhere perfect to live.
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