Coffee & Pot Plants

Coffee! Can you dig it?

This is not clickbait. We've all clicked stuff like that before, and it's annoying. This, hopefully, will be useful. Not "turn your old coffee into a candle! Step 1; buy a candle making kit!". Nonsense! This isn't like that. 

This blog will give you some practical advice on what to do with your spent coffee grounds. Some do's and don'ts. Even if the only thing you take away from this is a little knowledge of how to dispose of your coffee better, then I'll consider it a win. Reducing our waste is a good idea. Learning how to reuse it? That's an even better thing. Read on to find out more.


To begin, I'm going to start with a don't. 



A Sinking Feeling

What no to do!

Firstly, don't put your used coffee down the sink. We've all done it. I'll probably do it again, to be honest. It's the classic case of instant disposal. You get a clean coffee pot and sink. Bingo, that was easy! I can't see anything instantly wrong with what I've just done, so why fret? 

The truth is, if you dispose of your coffee down the sink every time, you've got trouble ahead. You may have even encountered it already, which means if you're still doing it, for the love of God, stop already!


Why not down the sink?


I want you to imagine a freshly brewed french press. You pour and enjoy your favourite FiXX observing the leftover ground coffee trapped at the bottom of your cafetiere. As you reach the end of your cup, you stop. There's sediment at the bottom of your cup—a perfectly normal by-product of brewing with a french press. These fine particles of coffee have sunk to the bottom of your cup and clumped together while you drank. Every lift and sip, they sank and stayed at the bottom.

So when you tip your french press down the sink, guess what? Some sediment will remain in the u-bend pipe. Most of the coffee will wash away so that you won't notice instantly. But the more you do it, the more sediment builds. The more residue there is, the more it will snare other bits of food, oil, hairs, whatever. Sooner or later, you'll have a blockage. And if it's bad enough, you'll have a plumber grade blockage. So just don't do it. There are better alternatives. 




Can You Dig it?

Can I compost used coffee?

So if not down the magic disappearing sink, then what? Well, just the bin is a better option, but a food waste bin (assuming you have one) is obviously better. But, if you're the gardening type and have your own compost pile, well, that's an excellent place for it. Filter papers and all. Coffee helps add nitrogen and potassium to your compost pile, which is a must for any superb compost. Keep in mind, though, that coffee grounds will be considered green compost material. This means to keep your compost pile healthy, you will need to balance it with brown compost material.

If you're not sure, this basically means you need to balance wet and dry additions to your compost heap. Brown/dry material adds bulk to your pile and allows air to circulate, keeping it healthy. They are generally brown in colour, but not always. Dry leaves, wood chips, sawdust, even old newspapers will work. Green/wet materials will add nutrition and are often green in colour, but not always. Food scraps, grass clippings, pulled weeds, used coffee all work here. 


But what else can coffee do in the garden? 




Tired & Thirsty Plants

Can I use coffee as fertiliser?

Maybe you're not the composting type. But you have some plants around the house/garden. Can your used coffee do anything for them? Yes, kind of. Well, maybe, it depends. Not all plants love coffee. Generally speaking, coffee has a tendency to raise the pH in soil, making it more acidic. This isn't a problem for plants that like acidic soil. However, not all do, so you must know what your plant likes before chucking your coffee grounds in on it.



How do I ckeck the pH of soil?


There is an easy way to check if you're unsure what type of plant you have. Take two tablespoons of soil from your plant of choice. Put it into a container and submerge it with vinegar. If the soil is acidic, nothing will happen. That's a good thing for your used coffee. But, if the soil sample is alkaline (not acidic), the soil will begin to foam and bubble, and the plant won't like your coffee. No matter how delicious it was. So going forward, I'll assume you know the following advice is based on the fact that you know what your plants like and do not like.


To begin with, sprinkling and adding used coffee to the topsoil around the plants in your garden will add nitrogen and help the soil's air circulation. This will encourage worms and microorganisms to do their thing. Evidence suggests that coffee works as a pesticide due to its caffeine content, keeping slugs away. Apparently, cats don't like it either. But my experience with cats suggests they don't like most things. 



Is it ok for houseplants?


However, things get a bit complicated when it comes to house plants. Putting used coffee in the topsoil will add nutrition, but too much might cause issues. Coffee grounds are really good at retaining moisture and can make overwatering plants easier. The excess dampness can also encourage fungal growth. On that note, used coffee is excellent for growing your own mushrooms. But it involves getting spores and growing kits, so I'm not going into that now. Also, if you have leftover coffee in the pot, you can dilute it with water at a ratio of 1:1 to make a sort of plant feed to water your plants with. 


However, as with anything in life, too much of a good thing can be bad. So use your judgement and utilise this tip sparingly. Your plants with thank you for it.




Scrub the day away

Coffee body scrub.

Ok, so you don't have a garden or house plants. That's fine too. You are your own delicate little flower and, as such, want ways to help yourself grow and glow. No problem. Coffee has been known to help here too. Coarse ground coffee can work really well as a body scrub. Now, as an adult Irish male, my expertise in the world of exfoliation is limited, at best. But I have it on good authority that this is indeed a good use of used coffee. And my research has concluded there is indeed something to this. Caffeine is an antioxidant known to protect skin from damage caused by free radicals; however, like plants, not all skins like the acidity of coffee. So it is essential to know your own skin.



Test your skin first!


You can always do a quick patch test before you go rubbing coffee on your face. To do this:


  1. Wash a small part of your arm and pat it dry with a clean towel.
  2. Rub a small amount of coffee grounds into the clean area.
  3. Wipe off the grounds and wait 24 hours. If there is any redness or itching, you will want to avoid using coffee as a scrub.


So going forward again, I'm assuming you know your own skin or have done a patch test, and you're not planning to hold me responsible for anything. Ever.



How to make a coffee body scrub.


To make your scrub, combine

  • 60g of coffee grounds
  • 100g of granulated sugar (any will do. Coarse sea salt also works well)
  • 25g melted coconut oil 
  • 2 tbsp of water or more as needed.

Simply combine these ingredients until you've reached the desired consistency. You can replace the sugar with rolled oats if you prefer, and you can also add some baking soda to help reduce the acidity of the coffee. Simply scrub the mixture onto your desired area in a circular motion while in the shower and rinse off with warm water. 




Pot Luck

Pot Scrub!

If you're more of a pot scrubber than a face scrubber, well, I've got good news for you too. Mix two tablespoons of your used coffee with a tablespoon of dishwashing liquid. You can now use this when going at those baked on roasting trays and casserole pots. This will also work well on the sink itself. And who doesn't love a shiny sink! 


And if you're thinking this is counterproductive to my first point, well, don't worry. The amount of coffee going down the sink is minimal compared to a full french press. And I'll probably be right in guessing pots of coffee are more recurring than pots in need of heavy scrubbing. 




Try a little tenderness

Meat tenderiser?

So you've got yourself a lovely clean pot now. What to cook next? Well, if you've a nice piece of meat, do you know what works well as a tenderiser? Used coffee, obviously. All meats are made up of muscle fibres and proteins, and sometimes, this will give them a tough consistency. Tenderising meat before cooking breaks these fibres down, resulting in a softer texture. Salts, enzymes and acids are all natural meat tenderisers. And if you've been paying attention, you'll know coffee is acidic. It also contains enzymes making it an excellent choice for this task. Not only that, but it's also delicious. When combined with spices and sugar, the coffee brings a lovely earthy flavour. You can find our recipe for a Coffee Spice Mix here. Just substitute the fresh coffee for your used coffee and marinate for two hours before cooking. 




Wood it help?

Coffee varnish.

So you're about to sit down to dinner surrounded by healthy pot plants. You are simply radiating from your new exfoliation routine. You've prepared a fantastic meal with veggies from your own garden. Grown with love using your nutrient-rich compost, all accompanying a deliciously tenderised meat main course. You smile to yourself about the joy of reusing coffee grounds. And then you see it. A scratch upon your table. Deep and obvious. A blemish upon your perfect evening. If only there was some way to FiXX it!! (Drum roll, please) Well, there is!


Make a paste using only ground coffee and water. The finer the grinds, the better. If you've got a pestle and mortar, this will work perfectly. If not, just mash it with something heavy. You'll only need about a teaspoon worth to begin. Once you've got your paste, apply it to the scratched area using a cotton bud. Leave it to sit for five minutes, then wipe clean with a damp cloth. You can repeat this as many times as needed to match the colour of the wood. Just wait a few hours between each application. 




Get the stank out!

Coffee deodorizer

One of the few things we can all agree on is coffee smells fantastic. It is just one of those universally accepted truths. Like freshly mown grass, freshly baked bread, or fresh mint! It's just a welcome sensation for your nose. It smells so good even other smells like it! Coffee is incredibly good at absorbing odours and moisture from the air because it is hygroscopic. And this is one of the reasons why storing your favourite FiXX properly is important (you can read more about that here).


But if you have a need to get some stank out of something? Well, your used coffee is here to save the day again. Putting a small container of used coffee in your fridge or freezer for a few days will neutralise any odours. You can leave small containers dotted around the house in any area that needs it. Just remember to replace it with new grounds every couple of days. It will even help get rid of the smell of paint if you've just done a job around the house. Freshly ground coffee is particularly good at this job. But, who has unused coffee!?



In conculsion...


So there you have it. A, hopefully, helpful guide to reusing some used coffee. And if you have zero desire to try any of these, please just dispose of your used coffee as best you can. At least try to try!

If you don't have a food compost bin, ask a friend. Maybe reach out to a local gardening community; I don't know. Chances are, someone will have a use for it. If you're a cafe owner, ask your customers if any of them want it. You'd be surprised how many people want to take advantage of the good things used coffee can do. And if none of that works? Just buy yourself a candle making kit and make some used coffee candles!


Thanks for reading. 





  • Kevin Acheson

Kevin has worked in and around the coffee industry for over 20 years in Ireland, the UK, the Netherlands, and Australia.