Will Coffee Grounds Deter Slugs?

by Peter Taylor | Last Updated: 17 January 2021

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Will Coffee Grounds Deter Slugs?

If you’re a good plant parent, you would want to get rid of the slugs and snails in your garden, as these can cause more damage than other garden invaders. Several slug killers like sprays and baits are available in the markets, but can something as simple as coffee grounds deter slugs?

Coffee grounds will deter slugs because they are toxic and can slow them down. Some studies suggest that coffee grounds stimulate mucus production in slugs, making it difficult for them to crawl smoothly. However, dregs act like a pest repellent and are not always enough to protect vulnerable plants.

Read on to know more about how you can use coffee grounds to get rid of slugs, its advantages and disadvantages, why slugs dislike coffee, and a few alternatives, non-toxic methods that slugs are not fans of.

Why Do Slugs Dislike Ground Coffee?

According to experts, the effect of ground coffee on slugs is debatable, but most studies suggest that slugs dislike coffee. Although the exact reason is not clear, a few theories state why coffee grounds deter slugs:

  • Since the coffee grounds’ texture is abrasive and grainy, slugs find it difficult to cross them with their soft bodies.
  • The chemicals in caffeine can cause damage to the nervous system. As a result, slugs experience uncoordinated writhing, irregular heartbeats, and loss of energy.
  • Coffee grounds, in general, can be toxic to slugs and can slow them down.
  • Slugs detest the mere smell of coffee grounds, so they move far away from caffeine content.
  • The ingredients in coffee grounds stimulate mucus production in slugs. Consequently, the slugs will have a hard time crawling over their mucus.

Coffee grounds are widely used as a natural pesticide to get rid of mollusks like snails and slugs. Furthermore, caffeine can suppress weeds and eliminate fungal pathogens. It can even keep pets like cats, dogs, and rabbits away, minimizing the garden’s damage.

Pros and Cons of Using Coffee Grounds in the Garden

The advantage of using coffee grounds is that it keeps slugs, snails, fungal pathogens, and pets away from your garden. Furthermore, it is an excellent fertilizer that contributes to water retention, drainage, and aeration in the soil. However, it is not practical to put out a good portion of coffee every day.

Also, keep in mind that it is not good to spread a thick layer of coffee grounds on the soil. As the dregs stick together, plants won’t get enough water and sunlight. This can result in stunted growth and even lead to the death of the plants.

You can use coffee grounds temporarily to keep your garden plants in good shape. But in the long run, it is best to seek professional help or use alternative options to get rid of garden pests.

Having said that, if you have used coffee grounds that are going to the trash anyway, distributing it in your garden isn’t a bad idea.

How to Use Coffee Grounds to Get Rid of Slugs

If you are dealing with slugs in your garden, try using coffee grounds to eliminate the mollusk. The procedure is pretty simple. Follow these steps to keep pests away:

  1. Take some coffee grounds, preferably fresh ones.
  2. Sprinkle the grounds in a thin layer on the soil. Coffee grounds are acidic, so don’t go overboard with the sprinkling as too much acidity in the soil will kill the plants. Moreover, do not put the coffee on plant leaves where beneficial insects may be present.
  3. Add carbon-rich materials like dried leaves or newspapers to balance the coffee grounds.

Using Coffee Grounds in Garden

Gardeners love coffee grounds, not just because it deters slugs. Here are a few benefits of caffeine you should know about:

Coffee Grounds As Fertilizer

Caffeine is rich in nitrogen, due to which it is an excellent fertilizer. The microorganisms present in the soil love coffee grounds as it promotes their growth and attracts earthworms beneficial for plant growth.

Coffee also adds organic material to the soil and improves water retention, drainage, and aeration. Fresh coffee grounds are acidic, whereas used ones are neutral. Hence, try to use fresh grounds for acid-loving plants.

While sprinkling coffee on soil, mix it with materials rich in carbon. These include dried leaves, bits of wood, newspapers, etc.

However, do not use too much coffee grounds on the soil because it can do more damage than good.

Coffee Grounds As Mulch

Coffee grounds not only benefit the soil but also act as a good barrier to unwelcome guests in the garden.

The caffeine content in coffee beans suppresses other plants’ growth to reduce competition for space, sunlight, water, and nutrients. One obvious solution is not to sprinkle coffee grounds near seedlings, as their growth may be inhibited.

Will Coffee Grounds Deter Slugs? 1

Be careful not to spread a thick layer of coffee grounds, as it will form a solid crust that will prevent air and sunlight from entering the soil. Also, the ground particles stick together and form barriers, resisting water penetration. This will lead to the plants dying of thirst.

Use variable particle sizes of coffee grounds to prevent barrier formation.

Coffee Grounds as a Natural Pesticide

As mentioned already, coffee grounds suppress weeds and repel pests. Though it does not fully eliminate pests, it does the job to an extent. Additionally, caffeine keeps cats, rabbits, and dogs away, thereby minimizing damage in the garden.

But if you are a pet owner, remember that coffee is harmful to pets. While using caffeine to keep them away is good for your plants, see that your pet does not consume the coffee grounds.

Caffeine is a central nervous system stimulant that can instill the effect of drowsiness in pests. It can even kill many insects feeding on the plants.

Home Remedies to Get Rid of Slugs

There are a lot of ways to get rid of slugs other than using coffee grounds. These home remedies are natural and will not harm your soil. Besides, there is no need to spend your hard-earned money on slug repellents.

Use Plants That Deter Slugs

Certain plants give off a scent that slugs dislike. Planting them in your garden will prevent this mollusk from wandering around. A few examples of slug beating plants are astrantia, fennel, anise, and rosemary.

Use Wool Pellets

Slugs find the itchy and rough texture of wool very annoying. Spin wool to create small pellets and place them at different places in your garden. As they don’t like moving over the coarse texture, they are likely to find another place to chill.

Use Copper Tape

Copper reacts with slug slime to give a mild electric shock. Paste the tape on to plant pots, raised beds, or anything you want to protect from these hungry mollusks.

Set Up Organic Slug Baits

Using slug baits is an efficient way to get rid of slugs. All you have to do is sprinkle the bait on the soil. When the slugs come in contact with the bait, they stop feeding and die within a few days.

A good bait is one that is organic and unharmful to pets and other mammals. Slug baits with iron phosphate are the most accepted bait. Avoid using products with poisonous ingredients like methiocarb and metaldehyde, as these can be toxic to mammals.

Encourage Predators

The most effective way to eliminate slugs is to encourage slug predators like birds, toads, and badgers. Chickens are also widely used to get rid of slugs. This natural method does not pose any risks while contributing to the food chain.

Use Materials With Sharp Edges

Since slugs have soft bodies, they detest prickly materials. A few examples of such barriers include grainy sand, eggshells, needles, and thorns. The sharp surface hurt slugs, and they are likely to leave the area. Also, be careful not to go barefoot into your garden after leaving barriers with sharp edges.

Use Beer

Beer is not only a great beverage but also a slug attractant. Take a small container, and fill it with beer. Place the container on the ground where slugs are most active.

These mollusks will be attracted to the beer and gradually crawl onto the container. While trying to take a sip, the slugs will fall in and drown.

Ensure that the container’s rim is at least 1 inch above the base to prevent the ground beetles from falling into the beer. Ground beetles feed on slugs and are good bugs.


Overall, coffee grounds and gardening work well together. Using caffeine is a widely accepted natural way to get rid of slugs and other pests. Remember that a thick layer of coffee dreg on the soil can damage your plants. Therefore, sprinkle some grounds so that it forms a very thin layer on the soil.

Here is a video showing how coffee grounds affect slugs:

One thing to keep in mind is that many gardeners do not prefer using coffee grounds to repel slugs, simply because they could not obtain the desired results. Hence, you may want to have a backup plan in mind if it doesn’t work.


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