How To Make Caffeine Spray For Slugs And Other Pests 

I’ve tried almost every at-home remedy to get rid of slugs! To be honest, some are completely ineffective, while others perform marvelously. From my experience, a properly made caffeine spray will kill slugs and other pests. So, if you just want to repel them, this probably isn’t the spray for you!

Making a caffeine spray for slugs involves preparing a few ordinary cups of coffee. Seriously it’s not that difficult! Your major objective is to get a high concentration of caffeine in the spray. To make the slug spray as effective as possible, the fluid should include a caffeine concentration between 1% and 3%.

Want to make another natural insecticide? Check out our garlic-based repellent!

You can make caffeine spray out of coffee beans!

How To Make Caffeine Repellent: 


You must make your caffeine spray as intense as possible to be effective against slugs. I advise using normal coffee rather than instant coffee because regular coffee typically has a higher percentage of caffeine. Also, try to use a darker or stronger roast if possible. Simply put, the more caffeine in the spray, the more effective it will be.

Use about 1 oz of water per cup to brew 2-3 cups; do not add more water to dilute the coffee. Allow it to cool in a container, then add it to the spray bottle. Be sure to give the spray bottle a good shake before using it. Slugs will start chewing on your mulch or even your plants once you have sprayed the caffeine spray around your plants. They will unavoidably consume the poisonous, highly concentrated caffeine while eating.

I recommend using Lavazza’s beans! They’re great for a caffeine

Applying the Repellent

When using the caffeine spray, make sure to spray the area around your plants, not the actual plants. Although most plants won’t be affected by a small amount of caffeine, some will be if you spray the spray directly into them due to its high concentration. The issue with the extremely concentrated caffeine spray is that, when sprayed directly on the plants, the caffeine actually makes the soil more acidic.

You could notice that some plants, like blueberries, will grow even better because they require highly acidic soil. On the other hand, since this is still the most efficient method of killing the slugs, you should continue to simply spray the soil surrounding the plants.

Use After Rain 

The biggest error people make when employing a caffeine spray against slugs is employing the spray on a sunny day. Most slugs will emerge in huge numbers after a storm, as you have surely noticed, and rain tends to wash everything away, including the caffeine spray. Use the caffeine spray outside once it has stopped raining; you will get far better results.

Use in the Evening 

Even if it doesn’t rain much in your location, you’ll notice plenty of slugs emerging from their lairs during the cooler evenings. Spray in the evening as it is a good time for them to consume the mulch that has been applied. Spray around your plants and wherever else you believe slugs might be hiding, such as under pieces of wood, empty containers, etc. This will help you catch them before they cause any damage.

How Often Should I Use Caffeine Repellent? 

The caffeine spray should ideally be used once weekly, although this mostly depends on how well it works to kill the slugs. You might need to apply the spray more frequently than once a week if you live in an area with abundant slugs. If the first application yields positive effects, repeat the process for a few days until you observe a decrease in the number of slugs; after that, once a week should be sufficient.

Final Thoughts 

As you can see, it’s really simple to manufacture caffeine spray for slugs; just be sure to make the solution as concentrated as possible. The fluid will be more lethal to slugs with a higher concentration of caffeine.

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How to make caffeine spray for slugs?

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