What To Do With Leftover Coffee

leftover coffeeBold and simple, yet very concise in it’s calculated brilliance. That’s coffee, but what are we to do with the leftovers?

The grounds, the last bit of coffee in the carafe, or even the spent K-cups that are so scrutinized for their waste still have potential.

Certainly, there are parts of the brewing process that lead to waste. What can be done to combat this? You won’t want to throw away another leftover pot of coffee again after reading this.

Leftover Coffee and When To Drink It

Black coffee should be safe to drink if left out for long periods, though it probably won’t taste all that great.

If you’ve already added some kind of creamer or dairy product it’s recommended to make a fresh pot instead. However, the best practice here is to simply pour the cold coffee in a mason jar with a sealing lid for safe storage once it’s begun to cool.

Many coffee aficionados might not know this but there are two milestones in the lifetime of a pot of coffee. One occurs at the age of 30 minutes, when the coffee cools and loses flavor. The next is after about four hours, when the oils begin to degrade and the acidity sets in.

drinking leftover coffee

Heating up coffee in the microwave or on the stovetop won’t reverse the deterioration in the brew. However, drinking hours-old coffee isn’t dangerous in the slightest. If you have a penchant for storing coffee then perhaps it’s best if you apply the mason jar technique to stave off mold.

If it’s refrigerated, coffee will last for at least a week, as long as you didn’t pre-dairy it.

Unrefrigerated, coffee shouldn’t sit out for more than twenty four to forty eight hours. Even approaching hour twenty four isn’t the best. Mold isn’t the biggest worry here, but it should be noted that coffee is a great medium for growth if left out for weeks on end. More on that later.

Coffee, like water can absorb flavors from its environment which change its flavor (especially if it’s left in a particularly pungent place like the refrigerator), but even uncovered, glasses of water are drinkable for weeks after they’re poured. Unless water has something living in it, like flowers, it’s difficult for bacteria to survive in it. Drink up.

Coffee does have incredible anti-microbial properties, and the caffeine is shown in research to stunt growth of certain bacteria. Caffeine is left to inhibit certain bacterial strains from growing en masse.

Cooking with Leftover Coffee

Cooking with leftover brewed coffee

Cooking with leftover brewed coffee might not have been the first thing one thought of when the carafe of drip coffee wasn’t finished this morning, but it’s certainly an option.

There are many culinary uses for the bitter drink. Mocha flavored treats are easily benefited by cooking down the coffee and adding it a mix for say, chocolate pudding, hot cocoa or even home-made ice cream. Additionally, many beverages can benefit from a coffee-flavored ice cube.

Simply grab an ice tray and pour in that old coffee and freeze it. Coffee ice cubes can benefit a whiskey drink or even iced coffee, as to not water down the drink. Coffee or Americano too hot? Using your coffee ice cubes won’t water down your drink either.

Replacing water with coffee in various recipes could be a new way to experiment with your favorite dishes. Although coffee flavored Pad Thai sounds strange, maybe it’s the next big thing in the culinary world.

Watering Your Plants With Coffee

Coffee has many uses beyond the kitchen that’ll be covered here, but let’s talk about plants. Leftover coffee for plants is a great solution to your problems in the garden and the carafe. There’s a lot misinformation about composting with coffee and how the acidity treats your houseplants and garden.

Some plants crave more acid. If you have plants that need acid rich soil to flourish all you need to do is pour your leftover coffee into the soil of the plants to give them what they need. A little goes a long way, however, so be careful you don’t pour too much onto your soil.

Watering Your Plants With Coffee

Composting with Coffee Grounds

Many gardeners will take coffee grounds and apply it directly to the soil around plants as a fertilizer or a pest deterrent. Work the grounds into the soil around your plants carefully, on the top layer of soil only. Leftover diluted coffee works well like this too. The benefit of this practice is not only that coffee grounds act as a fertilizer, but unlike store bought fertilizer, it adds organic material to the soil, which improves drainage, water retention and aeration in the soil.

The used coffee grounds will also help microorganisms beneficial to plant growth thrive as well as attract earthworms.

Keep in mind that coffee grounds can add nitrogen to your compost, they will not immediately add nitrogen to your soil. They need to be processed in compost to release their nitrogen boosting capabilities.

Gardening experts report that coffee grounds lower the pH (or raise the acid level) of soil. Some kinds of plants really benefit from this, but take into account what plants you’re trying to grow.

It’s important to determine if spent grounds is what you’ll be using. This is most likely the case because coffee should be enjoyed too. This is where the added value of beverage and it’s after use comes in. Besides, putting coffee grounds down the disposal isn’t such a harmless practice.

The sediment of grounds can incur some buildup and later damage to your pipes in the long run. So it’s of great benefit to use your grounds for something!

Fresh coffee grounds are acidic. Used coffee grounds are more on the neutral side.

Acid-loving plants that love coffee are:

  • Azaleas
  • Hydrangeas
  • Blueberries
  • Lilies
  • Radishes
  • Carrots

Coffee is particularly favorable to carrots. When you get your starters ready for the season. Before you sow carrot seeds mix up used and dried coffee grounds. This gets plenty of nutrients to these coffee lovers and helps growth immensely.

Don’t overuse grounds though. It can be tempting if you produce a lot in your morning routine, but while the nitrogen boosting affects can help plants grow larger, it’s actually hindering their ability to produce flowers or fruit. Perhaps caffeine really does stunt growth!

When creating a compost for gardening there are a few factors to keep in mind. Newspaper ink and cardboards are not recommended. These mediums don’t aid in providing nutrition to your plants. More importantly, they are commonly treated or contain chemicals like ink and glues with toxicity to plants.

Leaves, grass, wood shavings or sawdust all have nutrient content and are great for our purposes in the garden. Here’s the rundown on composting:

  • Determine what container to use: Wood, plastic, metal. So long as your container is big enough for your purposes and isn’t going to break down over time. Decomposing plant matter can heat up in the summer months so be careful that your medium is sturdy. Spread grounds on the soil surface, then cover them with leaves or bark mulch.
  • Creating your mixture: You’ll want both brown and green plant matter. Greens are nitrogen-rich, tend to contain more moisture, and break down faster. Browns materials are carbon-rich, contain less moisture, and take longer to break down. Coffee filters, wood chips and dry leaves are ideal for the brown elements; Setting aside kitchen waste and grass clippings are of great value for the green elements.
  • Add grounds to your compost pile often. Some composters report that an effective mixture is thirty percent browns to greens ratio. Just make sure that when preparing the compost you’re layering one part leaves to one part fresh grass clippings to one part coffee grounds, by volume. This helps that everything is mixing and jiving together properly.
  • Mix, mix mix. Stir your compost pile weekly to mix in oxygen which aids the break down process.

Now that we’re off and composting and ready for the garden we should use some extra grounds to ward off harmful garden intruders.

Treating Garden Pests

treating garden pests with coffee

Sprinkling freshly used grounds around plants helps to naturally deter some pests. Though some insects seem to go for the brown gold others seem to disagree with coffee. Keeping cats, rabbits and slugs away certainly helps minimize damage in the garden. The jury is out on whether squirrels are adverse to coffee grounds. Squirrels can be the biggest enemy of a newly planted garden, as they tend to love digging up sprouts and seeds when possible.

Adding some cayenne pepper to your freshly used coffee grounds in a great way to get pests out of the garden. This makes the coffee grounds a good medium for the pepper. Often just putting the cayenne on top of the soil will leave it exposed to wind, rain, or just being buried by garden trespassers. This way you can get rid of garden terrorists in a non-lethal way.

One word of warning though: coffee grounds may not have much effect on pests, but they can be harmful to pets in large enough doses. It’s hard to say how much grounds would be troublesome to your cat or dog because the caffeine content tends to change from roast to roast, and grounds to grounds. But it doesn’t take much for your pet to ingest too much caffeine.

Most everyone knows a dog that insists on sampling anything that smells halfway agreeable, it would be wise preferable to section off your garden anyway, and make sure such things are inaccessible for your furry friends.

Coffee grounds are free organic matter, whether a by-product of your at-home daily brew or collected from coffee shops that are only too glad to give them away for nothing. If used with care and common sense, they are a worthwhile addition your compost heap and your soil.

Leftover K-Cups

After you’ve spent a k-cup or maybe you’ve unloaded the contents to make a drink, with your Keurig out of commission. Either way, these cups are great for making starters for any plant you can imagine.

The cups have excellent drainage for starters and are easily stored for future usage. Empty the coffee from the basin of the cup and fill with soil. Your seed starters need to be moist the majority of the time. Thus, close monitoring of your starter plant is advised.



cleaning with coffee

There are a couple ways to used coffee grounds for cleaning.

Freshly used coffee can be used like baking soda for absorbing food odors in the refrigerator and freezer.  Simply place the grounds in an open container and situate it in the back of the fridge, come back in a couple of weeks while you collect more grounds.

Once the grounds have sat for a bit and collected odors, remove them from the refrigerator or freezer, then add to the compost pile or use them for fertilizer!

Cleaning Your Grill

If your grill is caked with grease from session after session of outdoor barbecuing, it can be tough to get clean. The acid in coffee will easily cut through that grease so you can easily wipe it clean. This works best if you have a lot of leftover coffee. It’s worth mentioning that some coffees are more acidic than others, you can even prepare less acidic coffee specifically if you have health concerns.

Draw some warm water in your kitchen sink with the leftover coffee. Soak the grates of the grill and the acidity will help eat through the grime over the course of an hour. Additionally, grab a rag with some brew and lightly work it over the interior of the grill. This is an advisable way to get around using oven cleaner or other harsh chemicals.

You can also apply this technique to clean barbecue utensils or oven burners.

Make Coffee Candles

making coffee scented candles

Love the scent of coffee all the time, but maybe concerned about daily caffeine intake?

Perhaps it’s time to take leftover coffee grounds and make some candles.

Find some leftover mugs that don’t get used for containers, if you want to get very literal with the coffee them. if not select some jars, or glass containers. Though we all know you have a cabinet full, shunned by your favorite mug. Used coffee grounds are ready? Then here’s the rest of our materials:

  • Candle Wicks: These are easy to get or make yourself. Just don’t use anything too flammable.
  • Candle/Paraffin Wax: Easily acquired at your local super market or online in bulk.
  • Sauce pan: This doesn’t have to be particularly large, but it’s going to be your candle making pan from here on out. So choose an old, beat up one.

Also, have a funnel, some superglue or wood glue, and a spoon or a leftover chopstick from takeout.

Make sure your coffee mugs or selected containers are ready by washing and drying thoroughly.
Get your glue and purposed candle wick. Next glue the wick to the bottom of the container and stand straight up will it dries.

While you wait, melt enough wax to cover the majority of the wick. The funnel will come in handy when trying to pour into the container. As you start filling with wax, take your fresh grounds and every so often, make a layer of grounds mixing both the melted wax and the grounds evenly and away from the wick.

Before the wax solidifies, make sure to stir and cover the grounds. Once the cooling process is completed, there candle is ready for use.

There you go, not so difficult to make a great craft you can enjoy at home or as a gift. Regardless of how you’re using your leftover coffee it’s a great way to recycle something that otherwise would just get thrown out. But as we all know now, coffee is just to valuable to waste.

Brian Mounts

Head blogger, editor, and owner of "Top Off My Coffee", a website that has been educating readers about coffee brewing techniques and equipment since 2012.

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