You Should Save Your Coffee Grounds. Here's Why
If you drink coffee on a daily basis, and you've gotten in the good savings habit of preparing your own coffee at home, there's one downside to the whole process — you end up with a whole mess of soggy grounds that you can't just wash down the drain. Well, you could, but as the Bill Howe plumbing blog points out, coffee grounds tend to build up in your pipes and can lead to serious clogs. If you have a compost heap for your organic scraps, you can always toss your coffee grounds on there, as they're perfect compost material.
But compost isn't the only way in which coffee grounds can be recycled. They lend themselves to numerous other applications around the yard, the house, and even as a beauty product. One thing you should be aware of before attempting to put your old grounds to new use, is that if you're not going to use them right away, Garden Guides notes that they do tend to get moldy. In order to avoid any nasty surprises, you'll need to refrigerate any leftover grounds, or even freeze them for long-term storage.
Use coffee grounds to grow your plants
Garden Guides suggests using coffee grounds as either solid or liquid fertilizer. For the former, simply mix a handful or two of coffee grounds into the soil around your plants. To make a liquid fertilizer, steep a handful of grounds in 2 quarts of water for several days, then strain out the grounds and use just the liquid to water your plants.
Healthline reveals why coffee grounds are so good for gardens — they are rich in calcium, chromium, iron, magnesium, nitrogen, phosphorus, and potassium, all minerals that promote plant growth. Coffee grounds also help attract worms, which might not sound great to you, but your plants will love them. One more thing coffee grounds might be able to do is to help absorb some of the heavy metals that may be contaminating your soil.
Use coffee grounds for pest control
Healthline also explains that coffee contains compounds such as caffeine and diterpenes that insects find to be highly toxic. Coffee grounds can be used to keep away mosquitoes, fruit flies, and beetles. Just set out small bowls filled with coffee grounds, or else sprinkle them around any outdoor areas in which people (and bugs) tend to hang out. Sprinkling coffee grounds around your plants will keep away the snails and slugs, because these squishy little gastropods don't like to crawl over such a rough and bumpy surface.
You can even use coffee grounds on your pets as a natural flea repellent. Rub the grounds onto your just-washed furry friend, then rinse them off. This treatment may deter fleas and make your pet's coat smooth and shiny, and it'll be pretty awesome to have your pooch (or kitty) smell just like the inside of a Starbucks.
Use coffee grounds as a room deodorizer
You might think it's the fact that coffee grounds have such a distinctive fragrance of their own that helps them to neutralize other unpleasant odors, but they really owe their deodorizing properties to the fact that they contain nitrogen. According to Healthline, this has to do with the fact that nitrogen combines with carbon to eliminate the nasty stink from sulfur gases. Or something. Anyway, chemistry. However it works, it works.
If you want to harness the de-stinkifying powers of coffee grounds, you can put a bowl of these in your fridge and/or freezer to absorb unwanted odors, you can fill old pantyhose or socks with coffee grounds to make sachets that can go in your drawers, your car, your shoes, or anywhere else you'd be afraid to stick your nose in, and you can keep coffee grounds next to the sink to scrub the smell off your hands next time you chop onions or garlic.
Use coffee grounds as a stain
You know what a pain it is when you spill coffee all over what is inevitably a brand-new white blouse (since you never, ever spill on days when you're wearing black; what's up with that?), how you have to soak and scrub and recite magic incantations and even then, half the time, you can't ever get that darn stain out? Well, guess what? You can use coffee's super-staining powers for good as well as for evil!
Chemistry Cachet suggests you can mix a cup of coffee grounds with a cup of boiling water, let the mixture steep for half an hour or so, and then strain the grounds (again). Use the reconstituted coffee as a paint-on wood stain. It won't make the wood really dark, but it will add a nice light brown tint that helps to bring out the natural grain of the wood. You can also use coffee grounds mixed with water to stain paper, giving it a nice antique-y sort of finish.
Use coffee grounds for your skin and hair
VeryWell Health lists several recipes for DIY skin treatments using coffee grounds, including an exfoliating face mask, a coffee/sugar body polish, a foot scrub, and a lip smoother. They also offer the tip that a teaspoon of coffee grounds wrapped in a damp paper towel can be applied to puffy eyes to reduce swelling. Apartment Therapy shares the additional information that coffee grounds, massaged into wet hair pre-shampoo, can help to strip away any gunky buildup from all the hair products you've been using.
Healthline offers another way to use coffee grounds with your hair, saying coffee grounds can be used to make a natural hair dye that can darken your hair a shade or two and possibly help cover up a little gray. You'll need to mix about 2 tablespoons of coffee grounds with 1/2-cup of brewed coffee and 1 cup of leave-in conditioner. Let it sit for an hour or more, then wash, rinse, repeat (if necessary). This dye job won't be a permanent one, but it will be quick and cheap, and make your hair smell a whole latte better than any other hair dye.