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A weekly feeding with leftover coffee provides nitrogen
By
Colleen Vanderlinden
Colleen Vanderlinden
Colleen Vanderlinden is an organic gardening expert. She wrote the books Edible Gardening for the Midwest and Vegetable Gardening for the Midwest, and her writing has appeared in Mother Earth News, Northern Gardener, The Detroit News, and Birds & Blooms.
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Updated on 04/08/23
Reviewed by
Mary Marlowe Leverette
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Reviewed byMary Marlowe Leverette
Mary has been a Master Gardener for 30+ years and a commercial and residential gardener for 50+ years. She is a former Clemson University Extension Agent.
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Fact checked by
Emily Estep
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Fact checked byEmily Estep
Emily Estep is a plant biologist and journalist who has worked for a variety of online news and media outlets, writing about and editing topics including environmental science and houseplants.
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Is coffee good for plants? It's okay to water plants with leftover coffee or to add coffee grounds to the compost pile but learning when and why to use coffee in the garden will protect your plants. Only use black, unflavored coffee with this method to offer plants a source of nitrogen which can fertilize certain indoor and outdoor plants.
How Often to Water Plants With Coffee
Though it's tempting to pour what's left in your daily cup of coffee into your plants, it's best to stick to fertilizing with coffee once a week. If you decide to try watering houseplants or outdoor plants and vegetables with coffee, keep a close eye on your plants. If 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, or that you have to cut down on how often you water your plants with coffee or coffee grounds. Try feeding plants coffee once every two to four weeks and see how your plants tolerate the reduced schedule.
Coffee-Loving Plants and Vegetables
Plants that prefer more acidic soil may respond well to a weekly watering with coffee or sprinkling of coffee grounds. But take into consideration the plants that may prefer slightly acidic soil vs. plants that like very acidic soil. For example, roses and beans may prefer only very slightly acidic soil but blueberries prefer more acid. Here is a list of both indoor and outdoor plants that would love a sip of your leftover coffee:
Houseplants:
- African violets
- Phalaenopsis orchids
- Dieffenbachia
- Norfolk Island pines
- Nerve plants
Outdoor plants, trees, and shrubs:
- Azaleas
- Rhododendrons
- Siberian iris
- Lupine
- Impatiens
- Pine trees and shrubs
- Holly bushes
- Magnolia trees
- Roses
- Lilly-of-the-valley
Vegetables and fruits:
- Blueberries
- Potatoes
- Cucumbers
- Peppers
- Carrots
- Radishes
- Beans
Using Leftover Coffee Grounds
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Coffee grounds can be 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. Coffee grounds sprinkled over the ground around acid-loving plants serve as a mild acidfertilizerfor them.Worms seem to love them, either in your garden or outdoor compost pile or in a vermicompost bin.
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 their 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
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When using leftover liquid coffee for plants, it is a good idea to first dilute your coffee with more water, especially if you prefer your daily cup of java on the strong side. But consider that in some workplaces, the only "watering"plants received is from emptying leftover coffee into the soil, and they often do quite well.
Tip
Liquid coffee can also be used to water a compost pile that has become too dry.
FAQ
Which plants like coffee as a fertilizer?
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. Be sure to check to see if your plant prefers acidic soil before using coffee or coffee grounds as fertilizer.
How often can you water plants with leftover coffee?
You should only water plants with coffee once per week. Keep that leftover coffee from the carafe in another container to use weekly.
Can I sprinkle coffee grounds in my garden?
Coffee grounds work well as a fertilizer for many plants and their soil. Just sprinkle the coffee grounds on the soil around the plants.
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.
Grounds in the Garden. Texas A&M University AgriLife Extension.
