We get asked a lot about slugs. Specifically, "do your mulch mats deter slugs?" And the answer is yes – the coarse fibres of both the wool and the jute are deeply unpleasant for a slug to slither across, and that's before we even get to the nitrogen-rich goodness our felt shillies and garden felt add to your soil as they break down.
But did you know that there is something you could do with a bulb of garlic that could seriously turbocharge your slug-deterring efforts? Read on.
Does Garlic Actually Work on Slugs?
It's not just an old wives' tale. Scientists at the University of Newcastle found in peer-reviewed research that garlic is genuinely one of the most effective natural molluscicides (that's the technical word for slug and snail killers, since you asked) out there. The research, published in the journal Crop Protection, also found that garlic can kill slug eggs in the soil. Bonus!
The magic ingredient is allicin – a compound that forms when garlic is crushed or chopped. Slugs and snails find it deeply off-putting, and in strong enough concentrations it can be lethal to them. The good news: it's completely harmless to humans, pets, birds, and the rest of your garden wildlife. The slugs just... go away. They're still out there living their best slug lives, just not on your hostas.
The RHS way to make "Garlic Tea"
The conventional recipe is to boil up bulbs of garlic, simmer it until it's soft, sieve it, then pour it onto the mulch mats: https://youtube.com/shorts/oNIt6LCQ-4I?si=wdf7Ne-VlVUqZEqL
This will make a good and garlicky decoction that will smell ghastly to slugs and snails. However, allicin is destroyed by heat. It starts degrading above about 60°C and by the time you've had a good boil on, it's pretty much gone.
The if you want a really potent brew, the secret is to make a cold water extraction instead. Here's how:
How to Make a Really Effective Garlic Slug Spray
You'll need:
- 2 whole bulbs of garlic
- A blender, food processor, or garlic press
- 200ml of cold water (to start)
- A fine sieve or piece of muslin cloth
- A jar for storing the concentrate
- A spray bottle or watering can
Method:
- Peel your garlic cloves and add them to a blender or food processor with the 200ml of cold water. Blitz until you have a liquid slurry. No blender? A garlic press and a bit of elbow grease works fine too – just crush each clove individually and stir into the water.
- Strain the mixture through a fine sieve or muslin cloth into a jar. You want to remove all the solid bits, otherwise they'll clog your spray bottle or block the rose on your watering can.
- What you've got now is your concentrate. You can use this neat on a serious infestation, or dilute it – roughly 2 tablespoons to a full 5-litre watering can – to treat a wider area.
- Store the concentrate in the fridge or outside in a cool, dry place. Make a fresh batch each growing season.
The cold water method keeps the allicin intact, which means the slugs sit up and pay attention to it. Simple, but important!
How to Use Garlic Water With Your Chimney Sheep Mulch Products
Our mulch range is already doing a lot of heavy lifting in the slug department, and garlic water works brilliantly alongside it. Here's how to get the best results:
Jute Mulch Mats
Our jute mulch mats already create a physical barrier that slugs aren't keen on, and they help retain moisture and suppress weeds at the same time. To give them an extra boost, water your diluted garlic solution directly onto and around the mats at the base of your plants. The scent acts as an additional deterrent around the protected zone. Reapply every week or so, and always reapply after rain – the allicin will wash away and you'll lose its effect.
Wool Felt Shillies
Our wool felt shillies are brilliant for piling around vulnerable plants – slugs loathe the coarse texture of the wool fibres. To supercharge them, lightly dampen the shillies with your garlic solution before you lay them around the base of your plants. The combination of the scratchy wool surface and the garlicky smell is quite the double deterrent. Think of it as a one-two punch for the slug-deterrence championship.
Garden Felt
If you're using our sheep wool garden felt for no-dig beds or to line the bottom of raised beds, water your garlic solution over the felt and surrounding soil at the start of the season. This can help deter slugs from even venturing into the area. Given that research found garlic can affect slug eggs in the soil, getting it into the ground early in spring is no bad thing.
Wool Garden Fleece
Slugs can sometimes find their way under fleece to get to tender young plants. A good watering of garlic solution around the edges where the sheep wool garden fleece meets the soil can help discourage them from trying their luck.
Tips for Best Results
- Start early. Apply your garlic solution at the beginning of the season before slug populations build up. Prevention really is better than cure.
- Be consistent. The allicin breaks down over time and washes away in rain, so regular reapplication (roughly weekly, or after every downpour) is key.
- Don't boil it. Cold water only!
- Combine approaches. Garlic water works best as part of a broader strategy. Our wool shillies, jute mulch mats, and garden felt already deter slugs physically – the garlic adds a chemical deterrent on top. Together they're a formidable team.
- Don't worry about the smell. It dissipates surprisingly quickly once it's on the soil. Just think about how strong it smells to the pesky molluscs!
A Note on Wildlife
One of the things we love about garlic as a natural slug deterrent is that it doesn't kill indiscriminately. Slugs tend to be put off and move away, rather than being poisoned – which means they're still available as food for hedgehogs, frogs, slow worms, and birds. In an ideal eco-garden, you want the whole food chain ticking along nicely, and garlic water helps you protect your plants without upsetting the balance.
