How to Use Coffee Ground as a DIY Slug Repellant That Really Works

You may have heard that a natural way to get rid of a pest infestation is with your morning cup of joe, but how effective is this method really?

While there’s certainly some truth behind the fact that coffee grounds can repel some bugs and insects, it turns out, it might not be as trusted a method as you originally thought.

If you’re noticing an increase in slugs in your outdoor garden, then you may have thought about sprinkling your grounds around your plants to steer the slugs away.

To know if that method will do the trick or not, we spoke to several pest control experts for their tips on how to use coffee grounds to repel slugs for a pest-free garden.

Can Coffee Ground Repel Slugs?

While you can definitely use coffee grounds as a natural method for repelling slugs from your garden, both of our experts say it should not be your only trusted solution.

“There’s a belief that coffee grounds are toxic to slugs due to the caffeine, but since most people use used coffee grounds that contain a low amount of caffeine, the toxic effect is minimal and hardly makes a difference at all,” Nicole Carpenter, president of Black Pest Prevention, says.

She adds that the thing that actually makes coffee grounds effective is their gritty texture, since it irritates the body of a slug and prevents it from being able to reach your plants.

Some insects are deterred by the smell of coffee grounds, but slugs are more sensitive to the acidity of the grounds, which causes them to dehydrate and eventually die. However, because your grounds may have a low caffeine count, you’ll have to sprinkle a generous amount on your soil, which may do more harm than good.

“If you apply too much of it, coffee grounds can also be harmful to the plants because they change the acidity of the soil,” Allan Bossel, pest extermination expert at Bed Bug Exterminator, says.

If you decide to try coffee grounds as a natural repellent for slugs, you’re only using it for the texture of the grounds, which slugs despise.

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How to Repel Slugs With Coffee Grounds

Even though coffee grounds aren’t considered the go-to choice among our experts, you can still attempt this hack as a natural way to repel slugs before trying another method. Here’s how to repel slugs with coffee grounds, according to our experts:

1. Dry your coffee grounds first to prevent mold from growing.
2. Sprinkle a thick 1–2 inches wide ring of dry, used coffee grounds around the base of plants.
3. Reapply more grounds after it rains or your grounds get wet.

6 Other Ways to Repel Slugs Naturally

Since coffee grounds can turn out to be a weak repellent for slugs, you may want to consider trying other natural methods to remove them from your garden. If you want to stay with natural solutions to avoid bringing chemicals into your garden, here are six other methods you can try:

• Combine iron phosphate with Spinosad: According to Carpenter, this is a 100% natural and highly effective measure for removing slugs. The iron phosphate acts as bait while the Spinosad provides a toxic substance that’s fatal to the bugs.
• Diatomaceous earth: This natural powder works to repel slugs from the sharp and jagged texture that dehydrates the slugs. If it rains, you will have to reapply the powder as it’s only effective when dry.
• Crushed eggshells: Laying down crushed eggshells around your garden as a barrier can be highly effective at repelling slugs. The sharp edges irritate the slugs and make it hard for them to crawl over.
• Sharp mulch: Like eggshells, sharp mulch is rough in texture, which slugs don’t like. It acts as a barrier that keeps them from getting into your garden from the mulch’s texture.
• Plant slug-repelling plants: Herbs like lavender, rosemary, thyme, or sage are repellent to slugs because of the smell. Plant a few of these herbs in your garden to release their scents that slugs despise to act as a deterrent.
• Vinegar and water: If you have vinegar on hand, make a solution of white vinegar and water to spray on slugs. The contact immediately kills the slugs from the acidity in the vinegar, which causes the slugs to dehydrate and die.