Why Are Coffee Grounds Used To Deter Deer & Does It Actually Work?

Frustrated with the pesky deer in your yard? While seeing Bambi out your window can feel like something of a fairy tale, when you take a look at your plants afterward and realize how much is actually missing, well ... it's not so fantastical anymore, is it? That's why we love to find crafty ways to deter the deer, especially if it's a kitchen ingredient that'll eliminate pests in your garden. And given that this one is already going to waste, you might as well use it, right?

For the coffee drinkers out there who have a green thumb, the idea of your leftover grounds repelling deer from your yard sounds a little too good to be true. Yet many plant and pest experts recommend coffee grounds for keeping garden critters like deer away. Does it actually work? Let's take a closer look at what the experts are really saying and whether it's actually worth saving those coffee grounds instead of tossing them in the trash or compost.

The truth about coffee grounds deterring deer

Despite how easy it may seem to simply dump coffee grounds in your garden to keep the deer away, the truth is there's no actual scientific evidence to support this claim. 

Pest expert Zack DeAngelis, owner of Pest Pointers LLC, speculates that the reason this tactic is believed to work is because of the smell of the coffee grounds. Deer have a strong sense of smell, and according to DeAngelis, the strong smell of coffee likely signals the appearance of humans, so deer will likely steer clear of the plants on your property.

Coffee grounds also have a bitter smell, which can be unpleasant for a deer that is typically drawn to a sweet-smelling plant. The scent of the leftover granules from the coffee may be overpowering enough to keep the deer away. Again, while there is no scientific evidence for this, and instances are purely anecdotal, that doesn't mean you shouldn't try this trick yourself. Especially when coffee grounds make a great fertilizer for your garden!

How to best utilize your coffee grounds to deter deer — and support your plants

If you want to give this deer repellent (and natural fertilizer!) a try, start saving your grounds. Particularly grounds from your hot coffee! Cold brew coffee has less acidity and bitterness compared to hot coffee, so if you're looking for smelly grounds for your garden, stick to the hot cup of joe. Store your leftover grounds in a container or a plastic sealed bag. Then each day, spread a small amount in the dirt surrounding your plants.

Now that you're using coffee grounds, can they replace your plant fertilizers completely? Unfortunately, the answer is no. While coffee does provide some potassium, phosphorus, calcium, magnesium, iron, copper, manganese, and zinc, the nutrient content is minor and not enough to properly fertilize your plants. If anything, the grounds help to support the soil surrounding them by feeding the microbes and improving drainage. However, experts still recommend fertilizing your plants to keep them thriving.

Keep in mind that deer are habitual creatures. At some point, they may get used to the smell and attempt to approach your plants again, so coffee grounds may not be a long-term solution to deter these animals. However, coffee grounds do work as a natural repellent for other pests, such as snails, slugs, ants, cats, dogs, and rabbits.