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Do plants like coffee


How to Use Coffee to Water Plants

Reviewed by

Mary Marlowe Leverette

Reviewed by Mary Marlowe Leverette

Mary been a Master Gardener for 30+ years and a commercial and residential gardener for 50+ years. She is a former Clemson University Extension Agent. She worked to develop the Riverbanks Botanical Garden that opened in 1995. Mary co-owns Marlowe Farms Apple Orchards.

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Fact checked by

Emily Estep

Fact checked by Emily Estep

Emily Estep is a plant biologist and fact-checker focused on environmental sciences. She received a Bachelor of Arts in Journalism and a Master of Science in Plant Biology from Ohio University. Emily has been a proofreader and editor at a variety of online media outlets over the past decade.

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The Spruce / Danielle Holstein 

Coffee is part of our daily life and a common gardening question is whether it's okay to water plants with leftover coffee or to add coffee grounds to the compost pile.

The answer is yes, in some situations using coffee when gardening is not only acceptable but a good idea. There are some caveats, though. 

Using Leftover Coffee Grounds

The Spruce / Danielle Holstein

Coffee grounds are a good source of nitrogen in your compost pile or when added directly to the soil in the garden. If added in fairly large amounts, they can raise the acidity level of the soil for acid-loving plants such as blueberries, azaleas, and rhododendrons. Coffee grounds sprinkled over the ground around acid-loving plants serve as a mild acid fertilizer for them. And worms seem to love them, either in your garden or outdoor compost pile or in a vermicompost bin.

And coffee grounds are regarded as an effective natural deterrent to garden pests such as slugs, snails, and ants. Rumors of coffee grounds repelling deer may be overstated. Deer are voracious eaters, and a few cups of coffee grounds are unlikely to make much of a difference. Coffee grounds will discourage a mischievous cat from roaming in your garden, but its effectiveness on rabbits and other common garden rodents is unknown.

Tip

If you're not a coffee drinker, don't forget your used tea leaves. They work great as a soil enhancer around acid-loving plants and add nutrients to compost piles.

How to Use Leftover Liquid Coffee

The Spruce / Danielle Holstein 

If you brew coffee by the pot, you may wonder if the cold leftovers can be used to water plants. Or, can the remaining half cup of cold coffee in your mug be poured into that potted pothos plant next to your desk?

The short answer is: maybe. It depends on the plant. Plants that prefer more acidic soil (such as African violets, Impatiens, Norfolk Island pines, Phalaenopsis orchids, and Dieffenbachia) seem to respond well to a weekly watering with 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.  

If you decide to try watering houseplants with coffee, keep a close eye on your plant. If the foliage starts yellowing or the tips of the leaves start turning brown, it's a sign that the coffee is adding too much acidity to the soil. It's not a bad idea to dilute your coffee with water, especially if you prefer your daily cup of java on the strong side. In some offices, the only "watering" plants received is from emptying leftover coffee into the soil, and they often do quite well. 

One caveat: if you add cream, milk, or sugar to your coffee, don't pour it into your plants. Ditto for flavored coffees. The sugars and fats can not only harm your plants and invite pests but can eventually result in a stinky mess. A plant watered with sweetened or flavored coffee may soon be overrun by fungal gnats or odorous house ants.

Article Sources

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Grounds in the Garden. Texas A&M University AgriLife Extension.

  2. Acid Soil Problems. Louisiana State University Agricultural Center.

  3. Fungus Gnats Tiny Flies Around Your Houseplants. University of Wisconsin at Madison Department of Entomology.

Coffee Used On Plants - How To Water Plants With Coffee

Home › Gardening How To › Soil, Fixes & Fertilizers

Soil, Fixes & Fertilizers

By: Amy Grant

Image by byryo

Many of us start the day with some sort of coffee pick me up, whether it’s a plain cup of drip or a double macchiato. The question is, will watering plants with coffee give them that same “perk?”

Can You Water Plants with Coffee?

Coffee used as a fertilizer is not exactly a new idea. Many gardeners add coffee grounds to compost piles where it decomposes and mixes with other organic matter to create some fantastic, nourishing soil. Of course, this is done with grounds, not the actual cold cup of coffee sitting here at my desk. So, can you water your plants with coffee proper?

Coffee grounds are about 2 percent nitrogen by volume, nitrogen being an important component for growing plants. Composting grounds introduces microorganisms that break down and release the nitrogen as it raises the temperature of the pile and aids in killing weed seeds and pathogens. Very useful stuff!

Brewed coffee also contains measurable amounts of magnesium and potassium, which are building blocks for plant growth as well. Therefore, it seems a logical conclusion that watering plants with coffee might indeed be very beneficial.

Of course, you wouldn’t want to use the cup sitting in front of you. Most of us add a little cream, flavoring, and sugar (or sugar substitute) to our Joe. While real sugar would not pose a problem to the plants, milk or artificial creamer won’t do your plants any good. Who knows what effect any of the many artificial sweeteners on the market would have on plants? I’m thinking, not good. Be sure to dilute before watering plants with coffee and don’t add anything else to it.

How to Water Plants with Coffee

Now that we have ascertained that we should use diluted coffee for plant fertilizer, how do we do it?

Coffee has a pH of from 5.2 to 6.9 depending on the variety and preparation. The lower the pH, the more acid; in other words, coffee is pretty acidic. Most plants grow best in slightly acid to neutral pH (5.8 to 7). Tap water is slightly alkaline with a pH greater than 7. Therefore, using diluted coffee for plants can increase the acidity of the soil. Traditional chemical fertilizers, the addition of sulfur, or allowing leaves to decompose on soil surfaces are methods to decrease soil pH levels. Now you have another option.

Allow your plain brewed coffee to cool and then dilute it with the same amount of cool water as coffee. Then simply water acid-loving plants such as:

Water with the diluted coffee just as you would with plain tap water. Don’t use this to water plants that do not like acidic soil.

Don’t water every time with the diluted coffee fertilizer. Plants will sicken or die if the soil becomes too acidic. Yellowing leaves may be a sign of too much acid in the soil, in which case, abandon the coffee irrigation and repot plants in containers.

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.

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Coffee as a fertilizer and 6 more ways to use grounds for plants and gardens

What tireless gardeners and gardeners try in the hope of lush flowering and an excellent harvest of green pets. Literally everything that is at hand goes into action. For example, natural ground coffee. There is so much grounds left after eating, so why not try it in the garden?

Experiments have shown that coffee can really be useful for gardening. Practical owners do not get rid of the thick, but use it both as a fertilizer, and to destroy pests, and as a means of combating plant diseases. The product is natural, which means, according to adherents of folk remedies, it will not harm either the land or the crops grown on this land. nine0003

According to summer residents, cucumbers, strawberries, radishes and carrots are especially fond of coffee. From flower crops - roses, gladioli and peonies.

Opponents of the use of coffee in the garden claim that this product makes the soil too acidic. Really fresh coffee has a high hydrogen index (pH) and is able to acidify the soil, but sleeping coffee that has lost its strength is completely neutral. It does not change the acid-base balance of the earth.

In addition, it is believed that coffee in the ground can provoke the appearance of harmful insects and the development of fungal diseases. In some cases, this is true, so before using coffee for plants, it must be prepared. nine0003

Firstly, the product should not contain any sugar or milk, so coffee straight from the cup is not suitable for plants. Secondly, the coffee grounds after brewing should be washed several times with clean water and then dried. And finally, coffee should be calcined (hold for 10-20 minutes in a hot thick-walled pan). After all these manipulations, the powder will become completely harmless and suitable for further use in the garden.

[!] To prevent the soil from starting to rot, become moldy and infested with pests, use only sleeping, washed and dried, and, if possible, roasted coffee without traces of milk and sugar on the site. nine0003

Coffee as a fertilizer

Growers and gardeners most often use dormant coffee as a fertilizer.
Coffee has been proven to be very rich in magnesium. Therefore, first of all, they are recommended to feed those plants that are deficient in this trace element. But how to understand that a culture needs magnesium? Very simple - on the leaves.

When magnesium is deficient, the interveinal sections of the leaf blade turn reddish-brown (sometimes dark yellow), while the veins themselves do not change color and remain green. Only old (lower) leaves suffer, young leaves remain green. Sometimes, with a lack of magnesium, the edge of the sheet is deformed (twisted) or brown spots appear along the edge of the plate. nine0003

In addition, coffee is believed to be rich in nitrogen, an element that is especially needed for young, recently planted crops, since it is nitrogen that helps to build up a dense green mass.

You can also determine the lack of nitrogen on the sheet. If this element is not enough, the lower leaves of the plant turn yellow, and the veins turn yellow first, and then the interveinal areas. The plant looks lethargic, slowly developing: no new shoots, small leaves, few inflorescences.

If all signs of magnesium or nitrogen starvation are present on the plant, you can try to feed it with coffee. nine0003

The spent coffee grounds should be mixed with the soil or simply poured into the bottom of the hole, after which the plant should be planted. In the case when the culture is already planted, coffee should be lightly dug in the top layer of the earth and watered abundantly.

Coffee against plant diseases

According to experienced gardeners, coffee can save plants from certain diseases. It is especially good for black spot and rose rust, diseases caused by pathogenic protozoan fungi. nine0003

In order to prevent dangerous diseases, in the spring, before the vegetation begins, coffee should be scattered around the rose and slightly buried, mixed with the top layer of the earth.

Coffee grounds to change soil structure

Why change soil structure? This is necessary so that too dense packed earth becomes loose, airy, and too light, on the contrary, more nutritious. Since ideal soil is rare, various additives are used to improve the properties of the substrate. One such additive is drunk coffee. nine0003

Coffee is especially good for soils with a high clay content. This soil has a very dense structure. It does not pass water and air well, which, of course, negatively affects the development of plants. When the clay earth is saturated with moisture, it is heavy and sticky, and when it dries, it hardens to the state of stone and is covered with deep cracks.

In order to make clay soil more loose, airy, water and breathable, it is mixed with minerals (sand, vermiculite, perlite) or organic matter (compost, sawdust, straw, fallen leaves). One good leavening option is coffee grounds. nine0003

It is very easy to use: mix the soil with dry coffee pomace and plant the plants. In this case, the total proportion of coffee in the soil should not exceed 10%.

Coffee in a compost heap

As you know, a compost heap is a place where gardeners and gardeners dump various organic waste. Grass, leaves, straw, cut plant residues (with the exception of diseased and infected plants) and even household organic waste, including used tea and coffee, can be added to the compost heap. nine0003

The share of coffee in the compost heap should not exceed 10-15%. However, it is difficult to exceed this ratio, since there are hardly so many coffee grounds on the farm. In addition to the sleeping grounds, even paper filters used for brewing a drink can be thrown into the compost heap. They will rot along with the rest of the organic matter.

Soil mulching with coffee grounds

Coffee grounds are sometimes used as mulch. (Mulch is a material that is used to cover the surface of the soil. Mulch saturates the soil with useful elements, retains moisture, preventing its evaporation, prevents the top layer of the substrate from overheating or supercooling, and reduces the number of weeds). nine0003

Coffee is quite suitable as a mulch, although there are some limitations. For backfilling, it is necessary to take clean grounds without the admixture of sugar or milk. It should be thoroughly dried, break up lumps and seals, and only then pour it onto the surface of the soil.

[!] If you mulch the soil with sweet coffee with milk residues, a variety of pests are likely to start on the surface.

In general, mulching coffee grounds is more appropriate for open ground. Under room conditions, such a substrate can turn sour, rot or become moldy. nine0003

Coffee as a remedy for aphids, ants, slugs and other pests

Many gardeners have noticed that drinking coffee helps fight some pests. Especially ants, slugs and aphids. Of course, it is unlikely to replace full-fledged industrial insecticides, but it is quite capable of coping where there are few parasites and it is important to maintain the ecological cleanliness of the site.

The use of coffee against insects is very simple - the thick must be thoroughly dried, and then thickly sprinkled with pest-infested soil. A sharp aroma will scare away insects from flower beds and beds. nine0003

If the pests attack the plant itself (like, for example, aphids), you should prepare a coffee infusion: pour 5-6 tablespoons of sleeping coffee cake into a liter of hot water, cool, let it brew for a day. For better adhesion, add 10 g of laundry soap. Pour the resulting solution into a spray bottle, and then spray on the leaves and stems.

[!] Coffee can not only scare away pests, but also attract useful garden helpers - earthworms. They like the pleasant smell of ground beans, so the worms willingly settle in the ground, mixed with sleeping coffee grounds. nine0003

Coffee for indoor plants

It would seem like a great idea to make a cup of coffee and pour the rest into a pot with a houseplant. And the plant is good, and nothing needs to be thrown away. Actually, the idea is bad. Experienced flower growers are categorically against coffee grounds on the ground surface of home flowers.

[!] The fact is that the used coffee used in this way is an excellent breeding ground for a variety of parasites: from moths and fungal gnats to mold fungi. Of course, under such conditions, the plant will get sick and may even die. nine0003

Of course, you can feed green pets growing in the room with sleeping coffee, but you should do it wisely. Do not pour the thick on top of the ground, but mix it with the soil during plant transplantation. The recommended proportion is 1 part thick to 10 parts soil. So the coffee will be evenly distributed in the pot and will gradually give nutrients to the roots.

Another method of using coffee for domestic plants is as follows: during transshipment, arrange the bottom layer of expanded clay, and then cover it with coffee grounds for 1.5-2 cm. In this case, coffee will serve not only as top dressing, but also as additional drainage. nine0003

***
One of the popular British botanists made an experiment: he watered the plants with fresh coffee. According to the results of the experiment, the Briton revealed that the cultures receiving coffee began to get sick and lag behind in development, and concluded that coffee is very harmful to plants.

In fact, the botanist made several mistakes. First, I used a fresh drink that acidifies the soil. And secondly, he brought coffee only to the surface of the earth, without deepening and without mixing it. nine0003

This is certainly not the way to do it, and in this case the coffee will really be dangerous for the plants. But if you use coffee grounds correctly, this supplement will not harm at all, but only improve the health of our green pets.



Coffee as a fertilizer and 6 more uses of coffee grounds in the garden

Coffee invigorates not only people, but also plants! If you are an avid coffee lover, do not rush to throw away the sleeping grounds. Make it "work" for your crop with our tips. nine0003

Many of us cannot imagine our mornings without a cup of aromatic strong coffee. This black drink has a truly "magical" effect on the body: thoughts become clearer, efficiency and mood increase. Did you know that coffee can affect plants in much the same way? Of course, with proper application!

1. Coffee as a fertilizer

Naturally, in terms of efficiency, coffee cannot be compared with any fast-acting fertilizer, and even more so it cannot replace complex top dressing. But it is worth recognizing that the introduction of dormant coffee grounds into the soil around the plants has a beneficial effect on them. nine0003

Decaying organic matter increases the biological activity of the soil. First, it saturates the soil with nitrogen. Secondly, it attracts earthworms, which loosen the soil. Thirdly, coffee, used as a fertilizer, allows plants to more easily absorb copper, magnesium, potassium and phosphorus from the soil.

Even though coffee contains 2% nitrogen, this does not mean that it can replace a complete nitrogen fertilizer. Since coffee grounds take a long time to decompose, the elements are released slowly. nine0003

There is an opinion that coffee significantly increases the acidity of the soil, therefore it is suitable as a fertilizer only for plants that require a lower pH level (conifers, rhododendrons, heathers, etc.). However, this is not quite true. Coffee is really "sour", but only fresh.

Sleeping coffee grounds have a neutral reaction - about pH 6. 5-6.8 (with an ideal acid-base balance of pH 7). For fidelity, it is advisable to rinse the thick with clean water before using it in the garden. nine0003

2. Coffee grounds compost

Composting used coffee is as easy as throwing the grounds into the compost heap. Again, given the controversy about its acidity, for greater peace of mind, it is advisable to pre-rinse it under running water.

Paper coffee filters can also be sent along with the grounds. All this will pereprete and will benefit the plants.

The only important thing to consider when composting is the correct selection of compost components. In addition to coffee grounds and other food waste, more "solid" components should be added to the compost pit: straw, wood residues, manure, grass clippings, etc. Coffee grounds should be no more than 15-20% of the total compost, otherwise it simply will not rot. nine0003

3. Coffee ground mulch

Many gardeners use coffee grounds as an environmentally friendly mulch. It is safe for plants, releases nutrients into the soil, enriches it with nitrogen, attracts earthworms, looks natural and is pleasing to the eye.

However, the main disadvantage of such mulch is that it can start to mold. To prevent this from happening, again, we advise you to rinse the thick with clean water and dry before spreading over the soil surface.


In addition, if you drink coffee with sugar and milk, naturally, they remain on the coffee grounds. Sweet mulch can attract ants and other insects. Therefore, it is necessary to wash the mass before drying.

4. Soil improver

If the quality of the soil in your area leaves much to be desired (it is too light, or, conversely, not enough air and moisture permeable), its structure must be improved. Good soil "breathes", easily passes air and moisture. To achieve this effect, you can add coffee grounds to the top layer of soil. nine0003

5. Growing herbs in coffee

As an interesting experiment, you can try growing herbs in a container filled with coffee substrate. Such a project called Urb was proposed by London-based industrial designer Blake Parkinson.

The main thing is to periodically feed seedlings with complex fertilizers in order to prevent nutrient deficiencies.

6. Pest barrier

It is believed that coffee grounds, scattered around plants, serve as a reliable barrier against slugs and snails, which are a real scourge of some crops. nine0003

In addition, according to some gardeners, coffee can not only scare away, but also destroy the larvae of insect pests, including mosquitoes and bedbugs.

Of course, in the fight against insects dangerous to the crop, you should not rely solely on coffee, but it will not hurt to bring it to your side as an additional ally.

7. Cat Repeller

If you are outraged by the fact that cats use your beds as a toilet, generously "sprinkle" the garden with coffee grounds. A strong coffee smell will discourage the tailed pranksters from any desire to relieve themselves in this place.

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