Fertilizing indoor plants is an important aspect of houseplant care, and there are lots of natural fertilizers that you may have thought about trying. One that many people ask about is whether you can use coffee grounds to fertilize indoor plants.
Can you use coffee grounds to fertilize indoor plants?- Coffee grounds can be used to fertilize indoor plants, but you are best to make compost with them first. Directly applying coffee grounds to indoor plant soil can cause excessive moisture retention, fungal overgrowth and even impair plant growth.
Coffee grounds are a very useful source of nutrients that indoor plants can use effectively, and a very cost effective fertilizer. Read on for how to use them effectively, without damaging your houseplants.
- Why Use Coffee Grounds To Fertilize Indoor Plants?
- What Are The Best Ways To Use Coffee Grounds To Fertilize Indoor Plants
- 1. Use Coffee Grounds To Make Compost
- 2. Make Liquid Coffee Houseplant Fertilizer
- 3. Add Coffee Grounds To The Potting Mix When Repotting
- Problems With Using Coffee Grounds To Fertilize Indoor Plants
- Excess Moisture Retention
- Promotes Fungal Growth
- Attracts Pests
- Coffee Grounds Can Actually Inhibit The Growth Of Some Plants
- There Are Much Better Alternatives
- Because You Asked
- USING THEM AS COMPOST
- USING THEM AS FERTILIZER
- USING THEM AS MULCH
- ADDING THEM TO YOUR SOIL AS A PESTICIDE OR INSECTICIDE
- KEEP THE CATS AT BAY BY ADDING IT TO YOUR GARDEN
- VERMICOMPOSTING – LET THE WORMS DO THE WORK
- ADDING THEM TO YOUR GARDEN TO SUPPRESS FUNGAL DISEASE
- WHICH PLANTS LOVE THE BLACK WASTE?
- USING IT FOR TOMATOES
- USING IT AS A LAWN FERTILIZER
- THEY ARE GREAT AS A FERTILIZER FOR ROSES
- BLUEBERRIES BENEFIT, TOO
- HYDRANGEAS LOVE THEM!
- WHEN NOT TO USE THEM IN YOUR GARDEN
- Is It Okay to Eat Used Coffee Grounds?
- Do You Eat Your Coffee Grounds?
- Are used coffee grounds a good fertiliser for plants?
- YOU SHOULD BE USING COFFEE GROUNDS FOR ONLY THESE PLANTS
- Help Your Houseplants Thrive with Coffee and Kitchen Scraps—Here’s How
- Coffee and Tea
- Banana Peels
- Orange Peels
- Cooking Water
- Nut Shells
Why Use Coffee Grounds To Fertilize Indoor Plants?
Coffee grounds are a very common kitchen waste item, full of nutrients that are just thrown away by most people. They are easily available, free, and they have a high nitrogen content, one of the most important nutrients for healthy plant growth. Using coffee grounds on indoor plants is also a good way to reduce household waste production.
People have been using coffee grounds in their gardens for years with reasonable success so it’s only natural for people to experiment with using coffee grounds to fertilize indoor plants. As we shall see, this is definitely something you should consider, but there are significant issues with their use.
What Are The Best Ways To Use Coffee Grounds To Fertilize Indoor Plants
While some people might be inclined to add coffee grounds directly to the top of the soil of their indoor plants, this is not recommended and can cause a number of problems. However, there are three great options for how your indoor plants can benefit from coffee grounds as a fertilizer.
1. Use Coffee Grounds To Make Compost
By far the best way to make use of coffee grounds is to use them to make compost. Add all your used coffee grounds to your compost pile and wait until your compost is ready to be used.
Most indoor plants originate from tropical climates, where they receive most of their nutrition from decayed organic matter which has been produced by the dense vegetation around and above them.
Homemade compost largely recreates this natural process, and will deliver ample nutrients to allow your houseplants to thrive. The high nitrogen content of coffee grounds (NPK 2.1-0.3-0.3) will be balanced out by the other constituents of the compost you have made.
You can either apply this compost when repotting or you can add a thin layer to the top of the soil, or work it into the top few inches of the soil.
Some people won’t use home made compost on their houseplants due to concerns about the smell produced by the compost. In my experience, this is not an issue. Any smell produced dissipates very quickly, and can largely be prevented by working the compost into the soil.
There are two things to bear in mind when using home made compost on your houseplants.
Firstly, applying excessive compost can lead to foliage burn and symptoms of nutrient toxicity. Add a maximum of one inch of compost to the pot to prevent this.
Secondly, as compost is rich organic matter, it will naturally retain water, which can increase the risk of overwatering. Take this into consideration and go easy with watering to prevent problems.
2. Make Liquid Coffee Houseplant Fertilizer
Although I wouldn’t recommend pouring coffee over the soil of your indoor plants, you can make a compost “tea” with your coffee grounds that will work well on your houseplants.
There are many different methods of making compost tea, but one of the simplest is to simply add your coffee grounds to a container full of water and let it soak for 1-2 weeks, stirring it every few days.
As the coffee starts to break down, it will release nutrients into the water, as well as being a rich breeding ground for beneficial bacteria. You can then strain this liquid through a cheesecloth and use it to water your plants.
This not only provides a good source of nutrients, but adds beneficial bacteria, which can improve the health of the soil and your plants.
3. Add Coffee Grounds To The Potting Mix When Repotting
As coffee grounds are an organic material, they release their nutrient content slowly as they decompose in the soil. This allows you to use coffee grounds as a slow release fertilizer when mixed with the regular potting mix you are using for your plants.
Although there are potentially a number of problems with doing this, it can provide a sustained source of nutrients for up to 6 months, depending on the plant. Coffee grounds are one of many natural houseplant fertilizers, but you should take care to use them properly, to get the best results.
Coffee grounds contain a large amount of nitrogen compared to phosphorus and potassium. Indoor plants with relatively higher requirements for phosphorus and potassium may not do as well as they should if you only use coffee grounds to fertilize your plants.
Using coffee grounds in your potting mix does come with a few problems which I will talk about in the next section.
Problems With Using Coffee Grounds To Fertilize Indoor Plants
Although we’ve discussed some of the ways you may wish to use coffee grounds to fertilize your indoor plants, it is important to highlight the negative aspects in a little more detail.
Excess Moisture Retention
Coffee grounds are exceptionally good at retaining moisture. Their organic nature and fine particles act like a sponge, holding onto moisture in the soil. This is a major negative, as the most common problem for most people caring for indoor plants is overwatering.
Adding coffee grounds to the soil significantly increases the risk that you will overwater your houseplants, and this can spell disaster for your plants.
If you do use coffee grounds on your indoor plants, either directly or as part of a compost, you can reduce the risk of overwatering by altering the composition of the soil that you use.
By adding more coarse sand or perlite to the potting mix, this will increase drainage, allowing the soil to dry out faster after watering, reducing the risk of overwatering and root rot.
Other options include using a porous pot, and/or a smaller pot. Both these changes will lead to faster drying of the soil, reducing the risk of overwatering.
Promotes Fungal Growth
This is more of an issue if you add coffee grounds to the surface of the soil of your houseplants. Coffee grounds provide an ideal breeding ground for fungal organisms, and this can lead to fungal disease in your plants.
It is particularly disappointing when you try to help feed your plants and promote their health, only to cause them a fungal disease which can do a lot of harm.
This problem can be reduced by ensuring the coffee grounds are worked well into the soil. Ideally, using coffee grounds compost, or adding coffee grounds when repotting will reduce this risk.
Mold will often grow on coffee grounds that are added to the surface of houseplant soil.
Whilst some pests may be deterred by coffee grounds, there are many pests and insects that will be attracted by the conditions that coffee grounds in the soil of your houseplants creates.
Once again, this highlights why adding coffee grounds to the surface of the soil is not recommended. Using coffee grounds to make compost is by far the best option, if you want to use coffee grounds to fertilize indoor plants.
Coffee Grounds Can Actually Inhibit The Growth Of Some Plants
There have been a number of small scale studies that have shown that coffee grounds added directly to the soil can actually inhibit plant growth, particularly in seedlings and young plants. This is thought to be due to the caffeine content of coffee grounds.
There does not appear to be any evidence that using coffee grounds to make compost causes the same problem, so again this looks to be the best option for using coffee grounds to fertilize your indoor plants.
There Are Much Better Alternatives
I suppose the bottom line is that using coffee grounds to fertilize houseplants is less than ideal. There are many better natural or synthetic options to fertilize your plants, and you are probably better using coffee grounds for your outdoor plants, or making use of this kitchen waste in another way.
Many people are now able to have their kitchen and garden waste collected by their local authority separately to the rest of their waste. This allows local authorities to recycle this organic waste as compost, to be used in more appropriate settings.
Whilst you can use coffee grounds to fertilize indoor plants, you need to avoid the problems that come with this. For most people, I would recommend using coffee grounds for your outdoor garden and using alternative options to fertilize your houseplants.
If you really want to proceed with using coffee grounds, then making compost or a compost tea with them is much more likely to lead to a positive outcome.
Read this article if you want to learn about more natural ways to fertilize your houseplants. Alternatively, see this article to find out which fertilizer I use on almost all my indoor plants.
Because You Asked
I tried adding used coffee grounds to my house plants and had a mold issue. What did I do wrong? Also, can I use the actual coffee as fertilizer?
-Dawn R., Madison, WI
Coffee grounds are an excellent addition to compost piles and outdoor gardens, but they can be tricky when it comes to indoor container gardening. When mold appears on grounds in a compost pile, it is eventually consumed by bacteria and turned into compost — no big deal. In an indoor setting, mold is unsightly and can pose hazards to human health. Fortunately, there are a few strategies you can take to successfully add grounds to your indoor plants.
- Reduce the amount and/or frequency of watering. A common reason for mold appearing on potted soil is excessive moisture. You may want to let the soil dry out a bit before adding grounds, especially if the grounds are already damp.
- If applying to the surface of the soil, layer the grounds thinly. Grounds can be compacted, retaining moisture and preventing aeration. This can result in an ideal environment for mold growth.
- Try mixing the grounds in with the top layer of soil. The variable particle size helps prevent compaction, thus improving drainage.
As for using the coffee itself as fertilizer, there seems to be little scientific evidence confirming its benefits but plenty of anecdotal evidence in the positive. Coffee is rather acidic, which can be beneficial to plants that thrive in acidic soil. However, it’s probably still a good idea to dilute any coffee you’re adding.
Oregon State University Extension Service
University of Illinois Extension
Are you looking for a way to give your plants a boost? Do you want to improve the soil in your garden but avoid using man-made chemicals? Adding coffee grounds to your garden is a cheap and eco-friendly way to add nutrients to your soil. Using them for gardening is not a new discovery, but it isn’t used as much as you would think. Many people don’t realize the benefits of adding the waste in your garden.
But are java bits good fertilizer? The research says yes. They can be used for composting, in your vegetable garden and even as lawn fertilizer. Your garden soil can benefit from the leftover coffee grounds you would usually throw away. And if you’re looking for a way to get rid of leftover food or vegetable peelings, then grounds are perfect for composting as well.
I’ve put together all the information you need to know about using coffee grounds for gardening. So read on and discover how you can take this waste product and use it to make your backyard thrive.
Table of Contents
USING THEM AS COMPOST
Using your leftover coffee grounds for composting not only helps your compost heap turn leftover food, fruit and vegetable peelings into nutrient-rich garden soil, it also reuses something that would ordinarily be thrown away.
It is much simpler than you think, just throw your coffee bits straight onto your compost pile or throw them (straight from the pot) into your compost bin. The great new is coffee filters are biodegradable as well, so you won’t have to worry about scraping them clean to throw them away.
The leftover bits add nitrogen to your compost pile and will improve the makeup of your garden soil.
The important thing to remember when you are using used grinds for composting, is they are a green compost material – this means that they are high in nitrogen. Other green materials are grass clipping and vegetable peel. In a good compost heap, you want a balance between green compost material and brown compost material. Brown material is high in carbon and includes eggshells, leaves, paper and cardboard. By getting the balance right in your compost heap, and having an equal amount of both, you will make sure you get the best quality garden soil.
To make sure you get the mixture in your compost heap perfect, add a third of leaves, a third of fresh grass and a third used grounds. You should make sure your compost heap is mixed regularly as the different materials need to sit alongside each other as they rot because they feed off each other.
Starbucks is one of the best places to gather used material for composting. Your local branch is happy to set some aside or give you a load of the used grounds at the end of every day. Just turn up with a clean, dry bucket or bag to put them in. You’re helping them avoid sending more waste to landfill and you get a large, regular supply of brewed coffee bits for your garden. It’s a win-win.
Compost can be stored in a heap or composting bin indefinitely as long as it is mixed well.
USING THEM AS FERTILIZER
Using coffee grounds as fertilizer is a cheap and eco-friendly way to give your garden soil a boost of nutrients. Now it might sound as if you need a Ph.D. in soil management to create your own fertilizer – but this couldn’t be further from the truth. In fact, you can add them directly to your garden soil.
But how do you do this and what is the best way to add them as a fertilizer?
Firstly, you want to get a large bag of coffee grounds (from a Starbucks or coffee shop as mentioned above) and a bag of topsoil.
You can mix equal parts grounds and topsoil to create a potting mixture or, if you are adding to flower beds, you can just sprinkle it straight on top. Take a handful and spread them onto the top of your soil. Make sure you don’t layer it thicker than half an inch or the remains could fuse together and create a solid crust which prevents water from getting through. Use a small fork or a rake to spread the coffee evenly in the garden soil and mix it in with the top layer of your flowerbed.
You can mix topsoil with the java remnants and then spread that in the same way. You could mix it in a large wheelbarrow and then walk it around your backyard, shoveling it out as you go.
If you are adding grounds directly, start with a small amount to test how individual plants react. Start by adding a level tablespoon of grounds once a week and then observe how your plants change or grow. Tweak the amount, or frequency you add them, to suit your plants.
While you may think the black material is too acidic for your garden soil, the brewing process actually removes the acidity but leaves all the nutrients and vitamins your plants will love. The grounds have nitrogen, phosphorous and potassium which are all easily absorbed by garden plants.
Leftover grounds can also be mixed with eggshells to create a perfect, rich fertilizer.
All plants crave nutrients so coffee grounds can be used with many different plants at different levels, further on we will go into which plants benefit from coffee grounds as fertilizer the most.
USING THEM AS MULCH
Using coffee grounds as mulch is a cheap and effective way to perk up your garden soil. Adding them to your garden is a brilliant way to give your soil texture.
As you can tell by just looking at them, the black kitchen waste is easily compacted due to its fine texture. Test this by taking a handful and squeezing them, you will see they quickly form solid lumps. This is brilliant for creating a barrier to moisture and air movement when laid on in a thick layer. Aim for one to two inches to create a water-resistant crust on the top of your soil. To create mulch however.
Use a thin layer of about half an inch on the top of your garden soil.
Then cover this with a coarse organic mulch layer, such as wood chips.
The organic material has an excellent reputation for germination of sugar beet seeds, cabbage, and soya beans. These plans react very well to the high nitrogen content at the seed germination stage. The increase in soil temperature, due to the high nitrogen content, allows seeds to germinate quickly and more successfully.
Compared to wood chips, grounds are a much cheaper and eco-friendly option. When you are using coffee remnants as fertilizer, you know it is near PH neutral but woodchips come from a wide variety of trees and it can be very difficult to know the acidity. Some woodchip mulch mixes actually have a bad reaction and will make your soil more acidic. This means using wood chips as a mulch can be riskier than coffee bits.
ADDING THEM TO YOUR SOIL AS A PESTICIDE OR INSECTICIDE
It is one of the main annoyances faced by gardeners. Tending your crops and vegetables only to see them attacked and destroyed by bugs and insects. But using leftover java grinds for gardening can also help you keep unwanted pests out of your backyard. Commercial pesticides are full of chemicals and man-made substances. While they can be effective, pouring a chemical concoction all over your plants or even vegetables can be bad for your health.
They offer a natural alternative. There is a great deal of anecdotal evidence that says they are a great slug repellent. A study in June 2002 for Nature, the journal which studies the natural world, found slugs and snails died after being sprayed with caffeine. While the amount of caffeine needs to be very high (about three times the amount in a regular cup of coffee) there are gardeners around the world that swear by using the material to deter pests.
KEEP THE CATS AT BAY BY ADDING IT TO YOUR GARDEN
While we all love pets, cats can be destructive (and messy!) presence in your backyard. They can dig up your plants and scavenge for food.
It has long been known that adding strong smelling substances to your gardens like orange, pepper or eucalyptus can put our feline friends off from visiting but brewed coffee remnants have the same effect.
While there are plenty of chemical-based products for repelling cats, or even mechanical systems that let of high pitched frequencies, coffee remnants are a more natural and eco-friendly approach to deterring your neighborhood cats. Caffeine is very toxic to cats, however, so caution should be used as to how much is spread about and where; you don’t want to have an unexpected and costly trip to the vet!
VERMICOMPOSTING – LET THE WORMS DO THE WORK
One creature that absolutely loves leftover coffee bits is worms. They are a gardener’s best friend and the use of worms for vermicomposting is a great way to enrich your soil and keep it full of nutrients. Earthworms turn organic waste into extremely high-quality garden soil. A family of worms is the best way to break down your compost heap and vermicomposting systems are a clean and efficient way to break down scraps and garden cuttings.
But why do worms like coffee grounds? It seems strange to think about it, but worms love the taste almost as much as humans. They tuck into kitchen scraps and vegetable waste as happily as if it was made specifically for them.
Worms need gritty food to aid their digestive system which is why the texture of grinds is perfect for them. Their internal organs are helped by the addition of organic grinds which makes them better at munching their way through your compost heap.
One of the recommended ways to attract worms to your compost heap and keep them there, is to line your compost heap with fresh coffee grounds regularly. Researchers at Cornell University discovered this can bring in the bilaterians from all over your garden.
ADDING THEM TO YOUR GARDEN TO SUPPRESS FUNGAL DISEASE
Another little-known fact is that grounds are actually anti microbial.
As the organic material rots in your garden soil, they can stop fungal disease including Fusarium, Pythium, and Sclerotinia. Studies show using them as part of your garden compost can help to prevent diseases from taking hold.
Dangerous bugs like E. Coli and Staphylococcus are also affected by having the black material in your soil and a test was carried out where cheese that was ripening was covered in grounds showed it slowed or stopped, the growth of harmful bacteria.
Beans, cucumbers, spinach, and tomato plants have all been tested with grounds and it has been proven that they stop the disease.
WHICH PLANTS LOVE THE BLACK WASTE?
The material can be used on hundreds of different plants and shrubs but there are some that react better than others.
Adding it to your garden improves the texture of your garden soil as well as the ability to drain away water after heavy rainfall. As they decompose, coffee grounds add nitrogen, potassium and phosphorous to the soil so any plants which need a rich source of these vitamins will react well to added coffee grounds.
Nitrogen craving vegetable plants include tomatoes, corn, spinach, and any leafy vegetable. Plants like roses, camellias, rhododendrons, and azaleas also thrive in nitrogen-rich soil.
Adding the organic waste to your vegetable garden can really give your crops a boost and you can be safe in the knowledge you are using only all-natural compost and fertilizer so the food you harvest from your backyard will be chemical and pesticide free.
USING IT FOR TOMATOES
Using the bitter material on your tomato plants can really give them a boost.
Tomatoes need nitrogen rich soil to grow healthy and strong fruit so coffee bits, with their high nitrogen content, are perfect. This helps the roots grow strong and boosts the tomato plant’s ability to produce chlorophyll – key for photosynthesis.
Coffee grounds are an eco-friendly fertilizer and also attract earthworms which will boost the soil around your tomato plants. Slugs, which are naturally attracted to tomato plants, will also be repelled by the used grounds.
The best way to use coffee grounds for your tomato plants is to mix it within your compost or topsoil to add the nutrients evenly through the mixture.
USING IT AS A LAWN FERTILIZER
Using the household material to make your grass greener might sound a little crazy, but the evidence shows it is very effective. And stronger grass means fewer weeds you’ll need your string trimmer for.
Grass loves grinds and it will make your lawn look greener and lusher.
The easiest way to spread coffee grounds is to do it when you water your grass. Mix around half a pound of coffee grounds with five gallons of water and you’ve got an inexpensive, and easy, lawn fertilizer. This way you won’t have the worry of clumps of coffee grounds scattered all over your lawn and you will make sure it spreads evenly by using a watering can to sprinkle the lawn.
You could also spread the leftover material by hand and then use a rake to evenly distribute the clumps of coffee. You should make sure it falls down between the grass and onto the soil itself which will make sure it adds nutrients rather than just sitting on the top.
If you’re composting, just add coffee grounds to your compost heap and once you have allowed it to break down and become a rich, well-mixed compost, you can use the compost with grass seed to cover any bald patches on your grass. The coffee in the compost will help keep the whole mixture moist and will help the grass seeds grow. It usually takes around three months to create a well-rotted compost mixture.
THEY ARE GREAT AS A FERTILIZER FOR ROSES
Rose bushes are one of the flowers that absolutely love coffee bits. These difficult to grow plants are boosted by the high nitrogen content in coffee grounds and by adding coffee grounds to your garden soil, you can loosen the texture and give your rose bush more room to grow. With with these benefits, and the fact coffee repels bugs, it is a great way to help your roses out.
But how do you make fertilizer for your rose bushes? You can just add the coffee grounds straight to compost as explained above, or even just sprinkle the dried grounds at the bottom of your rose bush.
Another method, similar to how you would use it on a lawn, is to mix the coffee grounds with water and pour it on your rose bush around once or twice a month.
BLUEBERRIES BENEFIT, TOO
The household waste can also boost blueberry plants. These hardy little plants don’t usually need fertilizer but they do get a boost from coffee grounds.
Like the nitrogen loving tomato plant, these berries thrive in a high nitrogen environment.
You can add the grinds straight to the soil with these plants. Just add four or five cups to the ground around your bush and then mix it well with the top layer of soil. This can be done as often as every two weeks.
HYDRANGEAS LOVE THEM!
Another beautiful flower which loves coffee grounds is the hydrangea. This plant benefits from the magic of coffee grounds.
They will change and improve the color of your flowers as the nutrients added by coffee grounds improve the plant. You will see brighter and more vivid colours on your hydrangeas just by sprinkling some coffee grounds into the top layer of soil or even mixing them with water and pouring over.
THE ACID TEST – COFFEE GROUNDS AND ACIDITY
There are lots of conflicting reports online about the acidity of coffee grounds. And you’ll be surprised to hear that there is a simple explanation.
Unused material (that have not been brewed or watered down) are acidic. But on the PH scale, which is used to determine how acidic or alkaline a substance is, a black coffee only measures 5. Numbers under 7 are acidic and above are more alkaline. 7 is neutral.
But the common mistake is to think that they remain at this PH after brewing. Once the grounds have been used in your morning cup of coffee, they are actually reduced and the PH level of used coffee grounds are about PH 6.5 or 6.8 – making them very close to neutral.
Of course, acidity changes marginally between different strengths of coffee so choosing a lower strength will see a lower pH level.
And different methods of brewing have an effect too. Using a coffee maker or cafeteria with hot water will remove much more of the acidity from coffee grounds than the newly-popular method of “cold brewing”. As cold brewing isn’t as harsh on the coffee as using hot water, the pH level won’t change as dramatically.
WHEN NOT TO USE THEM IN YOUR GARDEN
As mentioned above, cats don’t like coffee. And, in fact, it is very bad for them so if you have a pet cat it might be best to steer clear of scattering grinds directly onto your soil. A little mixed with compost, where it is unlikely to come into contact with your pet, could be alright. Just make sure you dig the grounds into the soil well to prevent too much of it getting onto your cat’s fur or paws.
So hopefully this list has helped you find out more about using organic material like coffee bits and gardening. We’ve gone over the pros and cons of adding grounds to the garden as well as adding some handy how-to guides for making the best lawn fertilizer, using coffee grounds for composting and putting coffee grounds in your garden soil.
Bringing earthworms into your garden, by using used toffee bits, will also make sure you have the best quality soil and give your plants every opportunity to flourish. They can also stop unwanted pests like slugs from damaging your crops and the caffeine content in coffee remnants will even keep neighborhood cats at bay.
When you are thinking about how to make sure your garden thrives and your plants look their best, these tips are invaluable to bear in mind. So if you have gotten some new information from this list, please comment below and share this article around with any friends and family that are looking for a way to boost their backyards.
Let us know how you do with adding grounds to your garden in the comments section and please share any tips you might have. Happy gardening!
Is It Okay to Eat Used Coffee Grounds?
Q: Is it okay to eat used coffee grounds? I like to put half the grounds from my morning brew in my oatmeal. And what about chocolate-covered espresso beans?
A: Small amounts on occasion probably won’t hurt—but we’d advise against eating a lot of the grounds or beans.
Coffee beans contain hundreds of substances, many healthful. Brewed coffee has been linked to a reduced risk of diabetes, Parkinson’s disease, gall stones, and some other disorders—and the grounds may have similar effects.
But some of the chemicals in coffee are potentially harmful. For example, coffee beans contain diterpene compounds, called cafestol and kahweol, which raise blood cholesterol. These are removed by paper filters when coffee is brewed, but people who drink a lot of unfiltered coffee (such as Turkish, French press, and espresso) may see their cholesterol go up. If you eat the grounds, you’ll also get these compounds.
A study in the American Journal of Clinical Nutrition in 1995 looked specifically at the effects of consuming used coffee grounds (about 1/4 ounce a day). After three weeks, blood cholesterol increased by an average of 26 points.
Eating the grounds or whole beans may provide an extra (welcome or unwelcome) laxative effect. You won’t get much of a buzz from the used grounds, since brewing extracts most of the caffeine. But an ounce of chocolate-covered whole coffee beans has about as much caffeine as in two to three cups of coffee.
Also see Coffee and Your Health.
Do You Eat Your Coffee Grounds?
I know exactly how you feel.
It started off slow for me. Just like it is for you now. I still remember it well. A French press is what got me hooked. I enjoyed the coffee, no doubt. But there was something about those last few drops. Something sublime. No, more than that. Something perfect.
For months I noticed it but could never put my finger on exactly what it was. I went over it in my head, time and time again, my mug by my side. And it finally clicked. It clicked on the last sip of my mug, while writing on the 193rd page of my logbook, I had to find a toothpick to remove a stuck ground from between my two front teeth. And I realized that was it. That was what I was looking for. The reason I liked my coffee so much more than any other. The source of perfection.
Of course I had to have more. Some men would be content to leave well enough alone. Glad to have found the source of perfection, but feeling no need to tamper with it. I am not one such man. I would grind finer at first. More grit, yes, but not enough. I moved on to grinding a gram more than I needed for my brew, spooning it off to the side in a small bowl. Right after the last drips from the press landed in my cup I’d follow them with a dash of grounds. The still rippling surface of the coffee sparkled as they fell in. It was better than I could have imagined. But I couldn’t just keep adding more and more grounds forever, there always seemed to be some ceiling, some point at which the whole brew was spoiled from them. And the grounds on their own never did it for me. I tried, believe me, I tried. But perfection needs context.
My brewing grew stagnant for years. Until a business trip to the middle east, we had a budding partnership with a Turkish company. My suitcase with my travel press and grounds bowl was lost at the airport. I had to stop in a local shop, I figured I could somehow instruct them to add some ground coffee to my cup. It would be enough.
I ordered a coffee and watched the finest grounds I’ve ever seen fill a copper pot. I watched the pot pressed into hot sand, a foam forming at the top and being poured into my cup. And again. And again, the seemingly bottomless pot foamed time and time again until my cup was full. Mesmerized by the process I completely forgot my request. I took a sip. Coffee and grit filled my mouth. It was perhaps, no it was certainly, the best coffee I’ve ever had. And the last few sips… My god, it turns out that there is something better than perfection. Heaven exists here on Earth. Heaven is Turkish coffee.
Nah, but really, you’re fine. Just keep doin what you’re doin.
© Ian L | Freerangestock.com
One question that’s relatively common — especially if you’re an infrequent coffee drinker, or if you were a bit overzealous because it was on sale — is, “Does coffee go bad?” The answer is, yes, it does. Okay, our work here is done.
Wait, you wanted to learn more? Here’s how to tell if coffee has gone bad, and why freshness matters.
There’s no such thing as a coffee molecule. Coffee — whether it exists in bean or ground form, or it’s sitting in front of you in a cup — is made up of as many as a thousand different compounds, including carbohydrates, amino acids, and lipids. With the passage of time, those compounds undergo physical and chemical changes that alter the aroma and taste of both the raw material and the finished product. Carbs go stale, lipids go rancid, volatile organic compounds evaporate, and other components change with exposure to oxygen (oxidation) or water. Even small changes can have a significant impact on the taste of your coffee.
How long your coffee will last depends on its form, as well as where and how it’s stored. If taste is your concern, your best bet is to store coffee in an airtight container somewhere cool, dry, and dark. Stored this way, ground coffee can be used for a few months past its expiration date, whole bean for up to nine months, and instant coffee for up to twenty years. You can also store coffee in the freezer, which greatly extends its shelf life (anywhere from one to three years for whole bean and ground coffee, and practically indefinitely for instant). However, freezing coffee practically destroys its flavor; the more interesting parts of the flavor profile vanish, and coffee that’s thawed from frozen will taste dull.
Peak flavor can vary, depending on the type of beans, the roast, and the brewing method used. In all cases, however, your safest bet is to use coffee as close to the roasting date (not the expiration date) as possible. Often, the expiration date is a year from the date on which the beans were roasted. The closer you are to the latter than the former, the less fresh (and less tasty) the coffee. If you’ve bought coffee and you’re not sure when you’ll use it, as happens if you usually drink regular but keep a can of decaf onhand for company, at least keep it sealed ’til you’re ready to use it. Most coffees are packed with nitrogen to slow spoilage, but once the seal is broken, you’re trading nitrogen for oxygen and humidity, both of which rob your coffee of flavor.
Since the preceding sounds a bit confusing (and Googling returns all sorts of contradictory information), let’s distill this to its essence. Fresh coffee is best, period. Freshly ground coffee, if you have the beans and a grinder; as close as possible to the date of purchase if you’ve bought your coffee pre-ground. If it looks or smells a bit “off” (rancid, moldy, or mildewy), throw it out. If it just smells flat, it’s going to taste flat, since the smell of coffee is such an important part of its flavor profile. Unless it’s gone moldy, you shouldn’t get sick from expired coffee, but just because you can drink coffee that’s past its expiration date doesn’t mean that it’s a good idea. Freshness matters!
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Are used coffee grounds a good fertiliser for plants?
“Just throw the coffee out into the garden,” a friend recently instructed me as I was helping to clear up the aftermath of brunch at his home. As I scooped the soaked ground beans out from the bottom of the cafetiere into a hedge in his back garden, I wondered to myself “do plants really like coffee?”.
When it comes to composting, the reason why coffee grounds are considered so useful is that over time they help to add nitrogen to your compost pile.
“Coffee grounds can be an excellent addition to a compost pile,” according to researchers at Oregon State University in a report from 2008 entitled Coffee Grounds Perk Up Compost Pile with Nitrogen, published on sciencedaily.com.
“The grounds are relatively rich in nitrogen, providing bacteria the energy they need to turn organic matter into compost. About 2 per cent nitrogen by volume, used coffee grounds can be a safe substitute for nitrogen-rich manure in the compost pile.”
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But when using coffee as a fertiliser and directly feeding plants with it, it’s important to note that not all coffee is good for all plants.
“Generally, adding organic material to the soil is good for your garden, since bacteria will feed on it and break it down into more nutrients the plants can use,” writes Ashley Hamer for a 2018 piece on curiosity.com called Whatever You Do, Don’t Put Coffee Grounds In Your Garden.
“But even coffee-ground gardening advocates include a few words of warning. Coffee grounds are highly acidic, they note, so they should be reserved for acid-loving plants like azaleas and blueberries. And if your soil is already high in nitrogen, the extra boost from coffee grounds could stunt the growth of fruits and flowers.”
However, according to Gardening Know How (gardeningknowhow.com), you can combat this level of acid in the coffee grounds by being careful about which grounds you use.
“Many people feel that coffee grounds lower the pH (or raise the acid level) of soil, which is good for acid-loving plants,” writes Heather Rhoades on the website. “But this is only true for unwashed coffee grounds. Fresh coffee grounds are acidic. Used coffee grounds are neutral. If you rinse your used coffee grounds, they will have a near neutral pH of 6.5 and will not affect the acid levels of the soil.”
Rhoades advises gardeners to work the coffee grounds into the soil around the plants and notes that using leftover diluted coffee works well in this way too.
If you want to move beyond the garden, other commonly suggested uses for leftover coffee grounds include a natural skin exfoliator, a cleaning product particularly useful for scouring old pots and pans, and keeping a bowl of coffee grounds in your fridge to neutralise odours from strong-smelling foods.
YOU SHOULD BE USING COFFEE GROUNDS FOR ONLY THESE PLANTS
Spring is here and it’s time to get that garden started again. You might have heard that coffee grounds can be used to help plants grow and be utilized in mulch and fertilizer. But coffee is slightly acidic so you want to be careful how you utilize it and which plants you use it on. Make sure you use The World’s Strongest Coffee for the best results.
Plants that prefer a higher acidity in the soil are those that usually can grow in any light. You can pick up a cheap soil pH meter on Amazon and test your soil before adding coffee grounds to it. Also, a lot of store-bought potting soil will tell you the pH on the packaging. Acidic soil is under 7.0 on the pH scale, and unless you have very acidic soil you can grow most fruits and vegetables, some flowers and shrubs too.
Take used coffee grounds and mix them with your soil about six inches into it, or mix them with your compost or mulch. Only use about one half an inch of coffee grounds per four inches of mulch or fertilizer. Make sure they are cooled down before you start to mix them. Coffee grounds are considered a ‘green’ organic material, so as a rule of thumb, you want to make sure to add enough ‘brown’ material to the mix – dried leaves or wood shavings work great.
- Lily of the Valley – loves acidic soil and can grow in any light
- Azalea Bush – also likes a more acidic soil but prefers some shade
FRUITS AND VEGETABLES:
- Wild Strawberries and Blueberries – thrive in acidic soil
- Sweet Potatoes
You can play around with different growing methods, soil and mulch compositions to really dial in the powers of coffee grounds! The great thing about coffee grounds is they are rich in nitrogen, as well as some potassium and phosphorus, all of which plants crave.
Remember again to mix the coffee grounds you use well especially if you own a dog. The smell of coffee might be enticing to your four-legged friend and you don’t want them to get sick eating all that dirt and coffee.
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Help Your Houseplants Thrive with Coffee and Kitchen Scraps—Here’s How
We all like to save a little money when we can, and if we can reduce waste at the same time, that’s even better. Perhaps that’s why the idea of using food prep leftovers on your houseplants is such an appealing one. Of course, composting is a great way to do this, but you may have come across advice for adding certain common kitchen waste items like banana peels directly to your indoor garden. Or maybe you’ve seen Grandma place eggshells or citrus peels around her peace lilies. While some of these may provide important nutrients and other benefits to houseplants, others may do more harm than good. Here’s a look at a few food waste products you’re likely to have in your kitchen and how to use them effectively on your plants.
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Coffee and Tea
Coffee grounds are fine additions to compost, and you can toss them onto the compost pile without any concerns. This goes for used tea leaves, too, and tea bags made of natural material and free of staples. Because decomposition needs to happen to release nutrients that plants can use, it is better to compost these items first rather than add them directly to your indoor garden. Otherwise, they will likely encourage mold growth in your plants’ pots (yuck!), and if added in too thick a layer, they can hinder water absorption.
What about the last splash of Joe in your coffeepot or the cold dregs at the bottom of your cup? These liquids contain nutrients like nitrogen that plants need for healthy growth, but they should be used sparingly. There’s such a thing as too much of a good thing for both people and plants! Before you pour, dilute it with the same amount of water and make sure to use only black coffee or tea. You might enjoy cream, sugar, and other additives, but your plants won’t. Wait to water until your plants’ soil is dry to the touch, and use your diluted leftovers only about once a week. Both brewed coffee and tea are slightly acidic and over time may change the soil chemistry in your pots too much. If you notice any yellowing on leaf tips, go back to just plain water.
Chicken eggshells are full of calcium, which plants need to develop a strong cellular structure. They also contain small amounts of iron, phosphorus, and magnesium, which are essential for healthy growth. However, eggshells can take years to decompose and release nutrients to plants, unless you grind them up very fine. The better way to provide some of these nutrients to your houseplants is to pour boiling water over the shells and allow them to steep for at least 24 hours. Then use the resulting infusion to water your houseplants. Some people like to use the crushed shells as a mulch on top of the potting soil to help hold in some moisture. If you want to try this, make sure to clean the shells very well in warm water first so they are free of any raw egg or membrane that might smell bad or attract mold.
All sorts of anecdotal evidence suggests that banana peels are nature’s miracle solution to about any plant problem, such as repelling aphids and removing dust from your houseplants. A few scientific studies have found that the peels can make an effective natural fertilizer, and numerous DIY recipes exist for feeding your plants with them. If you decide to experiment with the peels, realize that while they aren’t likely to harm to your houseplants, pests such as fruit flies find them quite attractive.
Citrus peels are one type of kitchen scrap not recommended for adding to a compost pile. Instead, you can use the peels from oranges and other citrus fruits to keep pets away from your houseplants—many cats and dogs avoid the scent. Cut the peel into pieces about one inch square and leave them on the surface of the soil to deter dogs and cats from snacking on your prized plants. Fresh peel seems to have the most effect, so feel free to add more whenever you enjoy citrus fruit and clean out the old, dried out pieces once in a while.
When you cook vegetables or eggs in water, some nutrients are boiled off into it. Once this water cools to room temperature, you can use it on your houseplants so they can benefit from those nutrients. This is an especially frugal tactic in regions that may be experiencing drought conditions that makes water rationing necessary. If you want to make this a regular practice, wait to salt your food until after cooking because salty water could burn your plants.
Hold onto those pistachio shells (and even peanut shells) instead of throwing them out. They can be used to help with soil drainage. After rinsing the shells to remove any added salt, line the bottom of your houseplant’s pot with empty shells to help excess water drain away from roots. If your concern is keeping a fussy plant moist, use the shells as a mulch layer on top of the soil to prevent quick drying.
By repurposing these kitchen scraps, you can save on fertilizer or other soil amendments. You’re also choosing a more natural, eco-friendly way to care for your houseplants while reducing waste.