You know that last bit of coffee that always seems to be left in the carafe? Don't just pour it down the drain — you can use it to fertilize your plants, both indoor and outdoor. Coffee grounds (and brewed coffee) are a source of nitrogen for plants, producing healthy green growth and strong stems. Coffee also contains calcium and magnesium — both of which are beneficial to plant health.
To use coffee as a plant fertilizer, you'll need to dilute it. It should look like weak tea. If you aim for about 1/4 coffee and 3/4 water, or even a half-and-half mix, in your solution (depending on how strongly you brew your coffee), that's about right, but you don't have to be fussy about it.
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You can use coffee fertilizer on your potted plants, houseplants and in your vegetable garden. Coffee and coffee grounds are acidic and, while there are some plants that love an alkaline soil and won't do well with the addition of coffee, such as lily of the valley, lavender and honeysuckle, some plants absolutely thrive in an acidic soil.
Here is a list, from Gardening Know How, of acid-loving plants that thrive on a good shot of joe, though there are many more not included in this list:
- African violets
- Blueberries
- Azaleas
- Phalaenopsis orchids
- Amaryllis
- Begonias
- Cyclamens
- Hydrangeas
- Bromeliads
- Gardenia
- Hyacinths
- Impatiens
- Ferns
- Roses
A good rule of thumb is to feed and water your plants once a week with a weak coffee solution. They'll appreciate the additional nutrients, as well as the water.
And while we're here, let's talk for a minute about those leftover coffee grounds as well.
They're a great source of nitrogen when added directly to the soil or placed into your compost pile (though some inconclusive studies argue against the efficacy of adding them directly to soil). Acid-loving plants such as blueberries, azaleas and rhododendrons will love them, as they raise the acidity level of the soil and serve as a mild fertilizer. Coffee grounds are also an effective natural deterrent to garden pests such as slugs, snails and ants. And, if you are a vermicomposter, your worms will love them!
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Originally Published: Jan 11, 2012
Coffee Ground For Plants FAQ
Are coffee grounds good for roses?
Roses are delicate flowers that need fertilizer every now and then. You can use coffee grounds as fertilizer for your roses, but use them in moderation as they can burn the flowers if used in excess due to the high nitrogen content.
Which plants like used coffee grounds?
Since coffee grounds have a high acidity level, they improve the growing conditions of many plants, including blueberries, hydrangeas, azaleas and hollies.
Which plants do not like coffee grounds?
Chinese mustard, Italian ryegrass, asparagus fern and geranium are just some examples of plants that don’t like coffee grounds and aren’t able to grow in soil that contains them.
How do you use coffee grounds on plants?
It is advised that coffee grounds are sprinkled thinly into the soil, at least a few inches from the plant’s stem to avoid damaging them.
FAQs
Is diluted coffee good for plants? ›
Coffee works great on many types of flowering indoor plants but can be used outside as well. Diluted coffee adds just enough organic fertilizer to encourage bushier, healthier plants.
Which plants do not like coffee grounds? ›In most cases, the grounds are too acidic to be used directly on soil, even for acid-loving plants like blueberries, azaleas and hollies. Coffee grounds inhibit the growth of some plants, including geranium, asparagus fern, Chinese mustard and Italian ryegrass.
Can you use unused coffee as fertilizer? ›Bury them in your compost heap instead. 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.
What happens if you water your plants with coffee? ›Coffee contains a lot of nitrogen, which not only kills off weeds and bacteria but can also help certain types of plants (a.k.a those that prefer more acidic soil) flourish. Plus, your daily cuppa also contains significant amounts of magnesium and potassium, both of which are key factors in plant growth and health.
How much do you dilute coffee for plants? ›To use coffee as a plant fertilizer, you'll need to dilute it. It should look like weak tea. If you aim for about 1/4 coffee and 3/4 water, or even a half-and-half mix, in your solution (depending on how strongly you brew your coffee), that's about right, but you don't have to be fussy about it.
How much coffee should I put in my plants? ›Too much of a good thing is possible, particularly for plants potted in containers. We recommend using about a teaspoon of coffee grounds per gallon of water.
Which plants like leftover coffee? ›Outdoors, acid-loving plants like azaleas, Rhododendron, Siberian iris, lupine, and any pine trees or shrubs will do fine if periodically watered with cold coffee. Liquid coffee can also be used to water a compost pile that has become too dry.
Do coffee grounds in plants attract bugs? ›Fertilize Your Garden
Spreading coffee grounds throughout your garden will also attract insects, such as, worms.
Your acid-loving plants like hydrangeas, rhododendrons, azaleas, lily of the valley, blueberries, carrots, and radishes can get a boost from fresh grounds. However, tomatoes do not like fresh coffee grounds; keep them out of that area of the garden.
Do plants like old coffee grounds? ›Fertilize Your Garden
Coffee grounds contain several key minerals for plant growth — nitrogen, calcium, potassium, iron, phosphorus, magnesium and chromium ( 1 ). They may also help absorb heavy metals that can contaminate soil ( 2 , 3 ). What's more, coffee grounds help attract worms, which are great for your garden.
What can I do with expired coffee? ›
- Body scrub. Coffee can be used as a body scrub. ...
- Can we use expired coffee on the face or hair? ...
- For hair growth. ...
- Deodorant. ...
- Coffee charcoal blocks. ...
- Fertilizer. ...
- Mosquito repellent. ...
- As wood stain.
Another reminder: The coffee you water your plant with needs to be black. That may seem obvious, but pouring out your leftover brew that contains sweeteners or dairy could attract pests, like gnats. Even if you're just using black coffee, you should stick to doing this only once a week.
Can you give plants too much coffee? ›Coffee is bad for plants for the same reason most people love drinking it - because of the caffeine. It means coffee is allelopathic - reducing the growth of other nearby plants that compete for minerals or water.
How do you make coffee fertilizer? ›Soaking used coffee grounds in water will break down some of the nutrients in the coffee to make a great fertilizer your plants will love. For this add 6 tablespoons of used coffee grounds to a gallon of water and let sit over night. In the morning stir and strain out the remaining coffee.
How often should I put coffee on my plants? ›How Often Should You Add Coffee Grounds to Plants? You can fertilize houseplants an average of 7 to 10 days in a row, but no more, as there is a risk of over-acidification of the soil. A cup of ground coffee should be added to the compost once a week.
Can you put too much coffee grounds in soil? ›Additionally, coffee grounds, though a good source of nitrogen, are acidic, and excess acid prevents the compost heap from heating up enough to decompose. She recommends that grounds make up no more than 15 to 20% of the total compost volume.
Do all plants like coffee? ›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.
What is the best fertilizer for hostas? ›Best Fertilizer For Hostas
The best hosta plant food is a slow release NPK 10-10-10 fertilizer. Those three numbers stand for the amount of Nitrogen, Phosphorus, and Potassium in the fertilizer. Slow release fertilizers feed the plant each time it rains or the plant is watered.
Coffee grounds make an effective mosquito repellent because of the strong smell. The coffee grounds will mask the scents on humans that attract mosquitoes - if they can't smell you they can't find you! You can also burn it to create an even stronger aroma - the same way citronella candles keep mosquitoes away.
Does coffee attract mice? ›Coffee's bitter compounds are responsible for its repelling effects. These compounds make the coffee unpalatable to rats and mice. They will avoid areas where there is the use of coffee grounds.
Does coffee attract roaches? ›
Roaches aren't particularly in love with coffee, but they're not known to be picky eaters either. They'll eat almost anything to get the energy and nutrients that they need to survive. So if they won't find anything else sweeter or more delectable in a cupboard, they'll definitely go for your coffee.
Which plants like Epsom salts? ›Epsom salt can improve the blooms of flowering and green shrubs, especially evergreens, azaleas and rhododendrons. Work in one tablespoon of Ultra Epsom Salt per nine square feet of bush into the soil, over the root zone, which allows the shrubs to absorb the nutritional benefits.
Which plants like eggshells? ›Plants like tomatoes, peppers and eggplants in particular will benefit from shell fertilizer, Savio said. The extra calcium will help prevent blossom-end rot. Broccoli, cauliflower, Swiss chard, spinach and amaranth are also calcium-packed and could use extra from eggshells.
Do snake plants like coffee? ›Yes. Snake plants typically need acidic soil that offers vital nutrition to the roots. There is a way to add a coffee ground to the snake plant. You can use the coffee ground as fertilizer.
Can you drink coffee that expired 3 years ago? ›The good news: No, coffee doesn't really “go bad” in the way that bread grows mold or a banana slowly rots on your countertop. And drinking coffee made from old beans won't make you sick, even if the expiration date has passed. (We can't vouch for the taste, though.)
Can you drink 2 year old coffee? ›Bottom line is that ground coffee will stay safe enough to drink pretty much indefinitely, barring any mold in the bag or a funky smell. But let's be honest, the coffee-drinking experience is more about the taste than anything else. If you don't like how it tastes, then you might as well dump it.
Can you put moldy coffee grounds in your garden? ›When grounds are stored they tend to develop green or blue-green fungus that looks like mold. The green fungus called Trichoderma, is very beneficial to the soil. The blue-green fungus is moderately beneficial. At any rate, moldy coffee is good to use directly in the garden, on your houseplants, or in the compost pile.
What can I mix with coffee grounds for fertilizer? ›Just combine 4-6 tablespoons of coffee grounds with one teaspoon of cinnamon and one cup of club soda in a large measuring cup. Mix together until combined. Pour the mixture over the soil of your plants once every two weeks and watch as your plants thrive.
How do you add coffee to soil? ›- Spread the coffee grounds directly on the soil. ...
- Spread on the soil and cover with leaves or compost or bark mulch.
- Add to the compost pile by layering the ingredients using 1/3 leaves, 1/3 fresh grass clippings, and 1/3 coffee grounds.
Plants that like coffee grounds also respond well to watering with coffee liquid. However, it is a fairly strong fertilizer, so this watering should not be done more than once a week.
Can you put too much coffee grounds on plants? ›
So it seems as though coffee grounds would be the perfect solution for gardeners in need of mulch. However, coffee grounds can actually harm the roots of seedlings by inhibiting growth if applied too thick. Also, coffee contains caffeine, which has been found to suppress the growth of plants.
Which plants benefit from coffee water? ›Apparently, coffee is a great source of nitrogen, and plants that enjoy more acidic soil can benefit from certain levels of nitrogen, like blueberries, azaleas, and rhododendrons.
Do old coffee grounds help plants grow? ›Fertilize Your Garden
Coffee grounds contain several key minerals for plant growth — nitrogen, calcium, potassium, iron, phosphorus, magnesium and chromium ( 1 ). They may also help absorb heavy metals that can contaminate soil ( 2 , 3 ). What's more, coffee grounds help attract worms, which are great for your garden.
4. Feed Your Acid-Loving Plants. Place coffee grounds around the soil of your acid-loving plants such as azaleas, hydrangeas, lilies, roses, rhododendrons, holly, gardenias and many others. Coffee grounds increase acidity and nutrients in the soil.