We've all been there — enjoying the sunshine in our backyard only to have it interrupted by mosquitoes and other creepy crawlies. But how do you keep them away without using artificial pesticides and sprays?
The answer lies in your used coffee grounds. Burn them like incense, and those pesky pests will be a distant memory.
How to Burn Coffee Grounds Like Incense
Here’s a step-by-step guide on how to prepare and burn coffee grounds like incense.
1. Dry Out Your Old Coffee Grounds
You can’t burn wet coffee grounds. So, you need to dry them thoroughly first. There are two common ways people get this done quickly.
A) Air-Drying Method
Spread your coffee grounds in a bowl or tray and allow them to dry out on a windowsill or in a warm. This method can take some time, so be patient. Avoid this method if you don't have a warm, dry room at your disposal. If the grounds take too long to dry out, they can become moldy. Burning moldy coffee can release harmful spores into the air.
B) Oven Drying Method
Spread the grounds evenly on a baking tray and dry them out at a low temperature of 175-200°F (79-93°C) for around 1-2 hours or until the grounds are fully dry.
Make sure to keep an eye on them from time to time to make sure they don’t burn and that the oven is not set too high.
2. Prepare Your Burn Bowl
Select a bowl or plate to be used to burn the coffee grounds on. Ideally, it should be able to take a decent amount of heat and shouldn't be one that you're particularly fond of. Burning your coffee grounds may stain the bowl with ash.
Create a small mound of dry coffee grounds, around one and a half inches in size. If you wish to, you can also add in cloves for their repellent qualities.
Make a small impression in the center of the coffee grounds. You can either place a wick of around two inches in length into the small impression or pour a small amount of lighter fluid into the dip you have created.
3. Select Your Burn Location
Next, you need to decide where you are going to burn your coffee grounds. Ideally, the spot should be outside but close to your house in order to have the desired effect. Just make sure that the wind direction isn’t going to blow the smoke in through any open doors or windows.
If you have children or pets, put the coffee grounds higher up on a table, windowsill, or a similar location for their safety. Speaking of keeping things safe, ensure there’s nothing flammable nearby.
4. Light the Coffee Grounds
It’s now time to light the coffee grounds. Light the wick or the lighter fluid in the center. You should see that the grounds will start to smolder and smoke gradually. If you find that there isn’t much smoke accumulation, you can cover the bowl with a damp towel. Just be careful not to smother it.
Why Should You Burn Coffee Grounds?
You should never burn the coffee you're going to drink. But burning old, used coffee grounds is a great way to repurpose them into garden heroes.
There’s one primary reason why some people choose to burn coffee grounds, and that’s to keep nasty pests and bugs at bay.
How Does Burning Coffee Repel Bugs?
The chemical makeup of coffee is what makes it so effective at getting rid of garden bugs like wasps, flies, and mosquitoes. We already know coffee contains caffeine, but it also has diterpenes, both of which work as natural insecticides [1].
The burning coffee releases these chemicals into the air, killing any bugs that get too close to the fumes and keeping away those that may be thinking about venturing into your garden.
The smoke itself also helps with this goal. It helps to cover up the smells that would normally be an inviting signal for various insects, like the aromas of flowers and fruits. If they can’t detect where the smell is coming from, they won’t be able to get there. Additionally, the smoke makes the air heavy, making it harder for bugs like mosquitoes to fly, and much like us, if they inhale too much of it, it is fatal [2].
What Other Creatures Are Repelled by Burning Coffee?
Bugs aren’t the only creatures that hate the smell of coffee. Cats and rats also can’t stand the stuff.
When it comes to cats, caffeine is toxic to them. So, if they smell it being burned in your garden, they are likely to keep away and are less likely to use your flower beds as a litter tray.
Coffee isn’t toxic to rats, but it disrupts their sense of smell. Rats have particularly sensitive noses, and the smell of burning coffee is unpleasant to them.
Not only that, it helps to mask the scent of food sources, meaning that the rat won’t be able to find them.
Another rodent — the squirrel — also hates the smell of coffee in much the same way.
Other Ways to Use Coffee in Your Garden
Aside from burning coffee grounds like incense, there are plenty of other ways to put your used grounds to use.
- Sprinkle-dried, used coffee grounds onto the soil to deter bugs like slugs, snails, and aphids, as well as to keep rats and cats away from your precious blooms.
- Put caffeine-rich coffee (like Cafely’s BanMe Coffee) onto cracks in the patio or where weeds gather to stunt their growth and kill them off. Make sure to avoid using it near your plants.
- Make a liquid fertilizer with three parts cold water to one part used coffee grounds. Leave to steep to a pale brown color, then use when watering.
- Add used coffee grounds to your compost or mulch to boost its power and support acid-loving plants.
Of course, as with people, some plants love coffee, while others are sensitive to caffeine and acidity. We’ve covered a detailed list of plants you can share your caffeine habit with.
FAQs: Burning Coffee
Here are some answers to some other burning questions you might have about using coffee grounds in this way.
1. How Do I Get My Coffee Grounds to Burn?
The two best ways to light your coffee grounds are by using a wick or a small amount of lighter fluid to start the flame. If your coffee grounds are not catching, it could be that they are too wet and need further drying out.
2. Can You Make Candles With Coffee Grounds?
You can make candles with coffee grounds in. Mix a tablespoon of coffee grounds into the melted wax, pour into your candle mold, and add the wick. This should be enough coffee grounds for a 12 oz candle.
3. Can I Burn Coffee Grounds Indoors?
If you burn coffee grounds indoors, it may be unpleasant, and the smoke can build up in your home. If not properly ventilated, the smoke may potentially irritate your lungs or set your smoke detectors off. If your outdoor space is limited, you could consider burning the coffee grounds next to an open window, making sure that the wind direction will carry the majority of the smoke outside rather than into your home.
4. What Coffee Has the Best Aroma?
While the best coffee aroma is completely subjective, freshly roasted and ground coffee will always have the most enjoyable and powerful smell, as the scent molecules will break down over time. You won’t get that gorgeous coffee smell from stale beans.
5. How Do I Put Out Burning Coffee Grounds?
Your burning coffee grounds will eventually go out when there is no more coffee left to burn. But, if you need to put the coffee grounds out beforehand, smother them with a damp towel. The damp towel will stop the burning process; however, the coffee may release a large amount of accumulated smoke. Be mindful when putting out burning coffee grounds to avoid smoke inhalation.
6. How Do I Dispose of Burned Coffee Grounds?
Make sure the coffee grounds are completely cool before getting rid of them. You can either dispose of them in your household waste, food recycling if you have it, or in a compost bin.
References
- Hussein, H., Abouamer, W., Ali, H., Elkhadragy, M., Yehia, H., & Farouk, A. (2022). The Valorization of Spent Coffee Ground Extract as a Prospective Insecticidal Agent against Some Main Key Pests of Phaseolus vulgaris in the Laboratory and Field. Plants, 11(9), 1124.
- Meer, R. (2022). Smoke as a form of personal protection against mosquitos, a field study in Papua New Guinea. The Southeast Asian Journal of Tropical Medicine and Public Health, 25(4).
