Does coffee repel slugs? 8 natural methods for getting rid of slugs in the garden

During the warmer months, you’ve probably noticed an increased number of slugs and are looking for methods for how to get rid of slugs. Whether that be on your garden path ideas or in your flowerbeds, they tend to congregate around plants or in damp areas of your garden. However, we've recently stumbled upon the claim that using coffee grounds in the garden could be a cost-effective method for how to get rid of slugs. 

So we put the claim to the experts to find out the truth, and they also shared seven other effective and natural ways to rid your garden of slugs this summer.

Do coffee grounds repel slugs?

There are conflicting views as to how successful using leftover coffee grounds is at fending off slugs. 

‘Caffeine is reported as poisonous to slugs, when ingested it causes severe dehydration and can therefore slow slugs down or even kill them. However, there have been many mixed reviews on the effectiveness of this method, some have reported poor results while others have managed to get rid of nearly all their garden slugs,’ says Steve Chilton, garden expert from LeisureBench.

Lucy Taylor, Manager at Vine House Farm corroborates this as, ‘in reality, there is little scientific data to back this up.’ While Robert Collins, pest control expert at Myjobquote.co.uk adds that, ‘field tests using coffee grounds around plants show that many slugs will simply crawl over the coffee grounds to get to plants while others avoid them.’

However, it may be worth trying if you have leftover coffee grounds – you don’t need to go out and buy new coffee grounds to try this gardening hack. Just remember to wait until they are fully dry and have cooled down, after you brew some for yourself, before using them in your garden.

‘Slugs may be deterred by the scent and texture of coffee grounds. However, the effectiveness can diminish over time,’ states Julian Hobday, Managing Director, PureSalt. So, you’ll need to reapply them every week or after any rainfall has washed them away.

‘Identify slug-prone areas in your garden or yard, such as around plants or in damp spots. Sprinkle a thin layer of coffee grounds around these areas, creating a barrier,’ he continues.

How to get rid of slugs - natural methods

There are a few other natural methods to repel slugs which are well worth considering.

1. Apply salt

An item that you should already have in your kitchen cupboards is salt. And if you don’t, you can pick up a bottle for around 70p.

Again, you’ll want to identify where the slugs are being drawn to and then create a barrier by sprinkling a line of salt around the areas that you want to protect or dissuade slugs from getting to. 

‘While salt can be effective in repelling slugs, it is important to use it sparingly and with caution,’ reveals Julian. ‘Excessive salt can harm plants and the surrounding soil. Consider alternative slug control methods if you have sensitive plants.’

According to Steve, ‘this method is therefore best used when directly poured on to the slugs rather than used as a barrier, we recommend looking for slugs late at night in cool damp locations.’

‘Although time consuming salt gives guaranteed and instant results by killing slugs through osmosis, where water is extracted from the slug resulting in severe dehydration. It is important to note that this method requires a large amount of salt in order to effectively kill each slug,’ he continues.

2. Seaweed

Because of the high salt content of seaweed, it works in a similar way to traditional salt. ‘Slugs are deterred from eating it, making it an effective border for susceptible plants. You can use fresh or powdered seaweed, as long as you make a continuous, wide border around your plants to discourage slugs from crossing,’ Lucy remarks.

3. Create a sand border

Much like with salt, the gritty surface of sand is rather difficult for slugs to cross. Again, you will have to top up your sand border after any rainfall but this can create an added hurdle for the slugs to get over before they make it to your plants or an area like a patio or outdoor kitchen that you’d rather they stayed away from.

4. Sprinkle eggshells

Another way to make use of food scraps that would ordinarily end up in the bin is by, ‘breaking eggshells into 1cm pieces and laying them in a similar fashion to the sand - a continuous border about 8cm thick creates a sharp, uncomfortable border that slugs will avoid crossing,’ Lucy divulges.

Opting for eggshells also has the added benefit that the nitrates in the shells will work to improve soil quality as they start to naturally break down.

5. Use beer to create a trap

Got a bottle of beer to hand? Well, the scent of beer actually attracts slugs, so creating a trap with beer in it can cause the slugs to drown and then feed other animals in your garden.

‘This method requires you to lay traps roughly every square metre to ensure full protection of the plant,’ suggests Lucy. ‘Fill some plastic containers like yoghurt pots with a little beer, dig holes around the plants and plant the containers in, allowing a lip of a centimetre or two to remain above the ground. Empty and refill the traps regularly, leaving the slugs to be safely scavenged by other animals.’

6. Utilise copper tape

‘Copper tape is probably one of the most popular and effective methods for repelling slugs. This is most effective when the copper tape is placed around the circumference of a plant pot, entryway or container, the copper will not kill them but rather deter the slugs from crossing due to its irritating nature,’ relays Steve.

Copper tape is a relatively inexpensive method but you will want to ensure that the tape is thicker than 4cm and to keep it clear of any debris, to give it the best chance to work.

7. Plant slug-repellent plants

You can also keep slugs away by planting slug-repellant plants in your garden. They especially hate herbs such as mint, rosemary, fennel, thyme and garlic, because of their strong odours.

'Hydrangea, ferns and euphorbia are good repellents for slugs as are geraniums,’ affirms Robert.

You can either surround the plants that you’re hoping to protect from slugs with a border of these plants or use them more sporadically around your outdoor space to keep slugs away from your doorways or seating areas.

It’s also always worthwhile making your garden or outdoor space somewhere where animals such as birds, frogs and hedgehogs – who eat slugs – can feed on them.