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 percentnitrogen 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.
Gardening tips, videos, info and more delivered right to your inbox!
Sign up for the Gardening Know How newsletter today and receive a free download of our most popular eBook "How to Grow Delicious Tomatoes."
FAQs
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. You can use coffee fertilizer on your potted plants, houseplants and in your vegetable garden.
How much coffee do you add to water for 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. Let the coffee grounds and water mixture steep for a few nights, stirring occasionally, then strain the liquid through a cheesecloth.
Can you water plants with diluted coffee? ›
The Spruce suggests that plants who love lower pH levels of soil (like African violets, rhododendrons, pines, etc) can occasionally be watered with cold coffee. Doing so about once a week (at most) seems to be the appropriate amount, and it won't hurt to dilute that unfinished cup with some more water before you do.
Which plants do not like coffee water? ›
Acid-loving plants, such as azaleas and blueberries, love coffee. However, tomatoes and lavender may not fare well if you use coffee to fertilize them.
Can I just sprinkle coffee grounds on plants? ›
While coffee grounds contain beneficial nutrients, plants can't utilize them straight from the grounds. The coffee grounds must first be broken down through composting or natural decomposition.
How often should you put coffee on plants? ›
You shouldn't sprinkle more than a thin layer around your plants, or else the coffee grounds can become impenetrable, preventing water from getting into the soil. If you evenly sprinkle coffee grounds around the plants once a week or so, the amount will likely be okay.
Which plants love coffee grounds? ›
Acidic-loving plants such as azaleas, blueberries, hydrangeas, rhododendrons, and roses will benefit from a sprinkling of coffee grounds around the base of plants. Vegetable crops that may benefit from coffee grounds include carrots, cucumbers, peppers, potatoes, and radishes.
How do I know if my coffee plant is overwatered? ›
TROUBLESHOOTING YOUR COFFEE PLANT
Drooping leaves - If she starts to droop she may be ready for a drink. Make sure your coffee plant has proper drainage to prevent overwatering. Yellow leaves/drooping yellow leaves - This is a sign that your coffee plant is getting too much water.
What does watering down coffee do? ›
Adding around 20 microlitres of water per gram of coffee – or around half a millilitre for a typical brew – can stop the grounds clumping together and improve the consistency and flavour of an espresso, says Hendon. “If you squirt a little water on it, you're gonna see a difference in brewing,” he says.
Can I put coffee grounds on my petunias? ›
Flowers: Coffee grounds can be used to fertilize a wide variety of flowering plants, such as roses, hydrangeas, and petunias.
However, there are some plants that you should avoid using coffee grounds on. Plants that prefer alkaline soil, like lavender and lilacs, can be harmed by the acidity of coffee grounds. Plants that are sensitive to caffeine, such as geraniums and some herbs, can also be affected by the presence of coffee grounds.
Do I put coffee grounds on top of soil? ›
To use coffee grounds as a fertilizer sprinkle them thinly onto your soil, or add them to your compost heap. Despite their color, for the purposes of composting they're a 'green', or nitrogen-rich organic material.
Do cucumbers like coffee grounds? ›
What Vegetables Like Coffee Grounds? Coffee grounds as a fertilizer can be used when growing vegetable crops such as potatoes, cucumbers, peppers, carrots, radishes, and beans. Root crops need magnesium and potassium, while nitrogen is indispensable for green crops.
Where is the best place to put coffee grounds in the garden? ›
Grass and most landscape plants tend to do well in soil with a pH of about 6.5. Peppers, potatoes, and many flowering shrubs thrive in more acidic soil. Coffee grounds sprinkled on top of the soil before it is turned can give acid-loving species the environment they need to grow best.
How to make coffee fertilizer for plants? ›
You'll need four to six tablespoons of coffee grounds, one teaspoon of cinnamon and one cup of club soda. Simply mix the ingredients until well combined and use on a bi-weekly basis for a slow release of nutrients without causing the soil's acidity levels to rise too much.
How much coffee do I add to my soil? ›
Like any type of fertilizer, coffee grounds are only effective when used sparingly. It is never a good idea to add too much, as that could do more harm than good. The proper proportion is usually around 4 to 1, or twenty-five percent of coffee grounds to mineral soils by volume.
Do tomatoes like coffee grounds? ›
Tomato Plants Like Slightly Acid Soil
The main reason that this idea that coffee grounds can help to fertilize your tomato plants is that tomato plants thrive in slightly acidic soil. Used coffee grounds can help soil become slightly more acidic when they are used as fertilizer.
