Can Coffee Grounds Really Repel Slugs?

Slugs and snails are a species that you definitely want them to keep out of your garden because of the devastating damage they do to plants. People often use chemical sprays to kill snails, but they don’t think there is another thing that is cheap to find and environmentally friendly. That is coffee grounds. Do something as simple as coffee grounds repel slugs?

Why do coffee grounds bring slugs away? 

Spanish slug Arion Vulgaris snail parasitizes on radish

The effect of coffee grounds on slugs is actually quite controversial, but many experts believe that slugs really don’t like this waste product.

They claim that the coffee grounds have a rather grainy texture and this interferes with the slugs. As a mollusk, crawling over coffee grounds is really difficult for them. According to a study by Robert G Hollingsworth who works at US Pacific Basin Agricultural Research Center, caffeine in coffee grounds causes slugs to writhe when touched, leading to irregular heartbeats. They are like poison to slugs, and slugs are also very afraid of the smell of coffee grounds, so using coffee grounds to keep slugs out of your garden can be a useful measure.

People often refer to coffee grounds as extremely useful waste for the garden. Not only do they repel slugs, but they are also an environmentally safe insecticide. Their scent keeps slugs as well as animals like squirrels and rabbits away. This will keep your garden protected from a lot of damage.

How do you use coffee grounds against slugs?

Closeup detail of coffee ground in a wooden bowl

Coffee grounds help repel slugs, so how do we use them to get the best results?

Actually, using coffee grounds to prevent pests like slugs and snails is very simple.

First, make sure your coffee grounds are fresh because they will have a rougher texture that will upset slugs.

Next, spread the coffee grounds over your potting soil. Note that, spread a very thin layer. The reason is that coffee grounds are known to be a fairly acidic fertilizer, if the soil contains too much acid, it will affect the growth of plants. There are plants that can live in acidic soil and even grow very well. But that’s just with the right amount for the plant to grow, too much will lead to backfire. If your plant is really not suitable for highly acidic soil, sprinkle the coffee grounds in a circle away from the base of the plant to get the effect without affecting the life of the plant.

Some ways to keep slugs away from your garden

Man farmer watering a vegetable garden in the evening at sunset

Besides using coffee grounds to keep slugs out of the garden, there are many other ways that also bring very good effects.

The very first way is to clean up your garden. Clear around gardens, fences, and dark, hidden places so slugs can’t find shelter there. Besides, get rid of the fallen fruit and other tempting organic things they love. Leaves or grass in the garden can also be foods that provide food for slugs as well as provide them with a good environment to hide and lay eggs.

Next, water the plant in the morning. Do not water in the evening. Slugs are nocturnal and they prefer moist environments. That is why when you water them in the evening, it will create favorable conditions for them to thrive.

Another way is to start killing slugs early in their growing season. Slugs will start appearing in the spring or rainy season. If you kill them at the beginning of the season, it will be easier to have a small number of them because it will prevent them from spawning and multiplying quickly the next time.

The last way is to hunt them in the early morning or evening. This takes a lot of work and can be a bit intimidating for some people. However, if you do it regularly, the effect will come after a few weeks.

Pros and cons of using coffee grounds 

Using coffee grounds in your garden actually offers a lot of advantages. They are often used by gardeners as an eco-friendly organic fertilizer that is easy to find and cheap. Research by the Department of Chemical Engineering said that the nutrients contained in it like potassium, phosphorus, and nitrogen, make the soil environment richer and plants grow well thanks to those nutrients. Coffee grounds also make the soil able to retain a certain amount of moisture, suitable for moisture-loving plants.

Not only that, but coffee grounds are also a product to help repel pests that destroy crops. Their scent keeps rodents like rabbits, mice, and squirrels away. As well as the caffeine contained in it is a toxic substance for slugs. It also prevents the fungus from growing in the soil environment.

However, besides a host of advantages mentioned above, there are still a few disadvantages that coffee grounds bring. Coffee grounds contain a lot of acids, there are plants that do not like acidic soil environments, so they not only do not benefit from coffee grounds but also have limited growth and even lead to root rot. And if you spread too thick a layer of coffee grounds on the surface of the soil, sunlight will not be able to penetrate them and cause plants not to receive enough sunlight, affecting growth.

However, coffee grounds are still a product that you should not ignore if you are looking for a versatile fertilizer, moreover, it is extremely cost-effective and environmentally friendly.