Your cart is currently empty!
Get Event Reminders…
…twice a month by subscribing to our newsletter
Subscribe using the form in the page footer below.
Your cart is currently empty!
…twice a month by subscribing to our newsletter
Subscribe using the form in the page footer below.
You’ve heard that adding coffee grounds to your compost speeds decomposition and adds much-needed nitrogen to the compost. Coffee grounds are good for plants in the garden. We explain why and identify specific vegetables, plants and flowers that can benefit.
In a related article, read about coffee grounds and other techniques to improve soil.
Coffee grounds by weight contain about 10% nitrogen-rich proteins, which are vital for seed germination and plant growth. In this way, coffee grounds are good for plants.
Coffee grounds are highly acidic, they will lower the pH of your soil, making it more acidic. As a consequence, they can be beneficial to acid-loving plants.
Coffee grounds can contribute nitrogen to soil. Nitrogen is a key nutrient for plant growth and development. Coffee grounds help repel slugs and snails.
In scientific studies, adding coffee grounds has shown varying results, from creating a mildly acidic finished compost of 4.6 to an alkaline compost with a pH of 8.4(!). When composted coffee grounds were added directly to garden soil, researchers found that the pH of decomposing grounds was not stable. After showing an initial increase in acidity levels, the soil pH decreased shortly thereafter.
Blueberries, strawberries, carrots, radishes, roses, hydrangeas, rhododendrons, azaleas, lilies and hostas are some plants which benefit from more application of coffee grounds. Here’s a round up:
Plants that do not like coffee grounds are plants that do not like acidic soil, including tomatoes, lavender, pothos, rosemary, and orchids.
It is not a good idea to spread coffee grounds across your gardens. If applied too thickly, coffee grinds might actually injure seedling roots by impeding growth. Use coffee grinds solely on certain plants.
Coffee grounds have shown substantially positive results. As with any good organic mulch, coffee grounds:
In one recent study, researchers found that Starbucks’ coffee grounds contain .6% potassium, .06% phosphorous and 2.28% nitrogen. There was also a bit of copper and a trace of magnesium in the grounds. When applied as a soil amendment, the coffee grinds provided some nutrients right away and released some gradually. This makes them a good choice to give your plants an immediate boost along with ongoing nutrition.
Note that acidic levels are affected by the variety of coffee bean combined with the brewing method.
Bacteria and fungi break down coffee grounds when added directly to garden soil. As a result, decomposition creates humic substances. Earthworms pull coffee grounds into the soil and use them as a food source which improves soil structure.
Nitrogen is the primary ingredient for plant growth and coffee grounds contain a high proportion of nitrogen. But not every plant responds well to them. In fact, fresh grounds can be poisonous to some plants (known as phytotoxicity), so never let the grounds come into direct contact with roots or stems.
Coffee grounds can suppress seed germination and inhibit growth in many plants. To explain this, some scientists speculate that decomposition of coffee grounds releases toxic substances. These might be responsible for weed suppression. Other scientists have proposed that caffeine is the nutrient that causes this allelopathic activity. To be safe, never add coffee grounds directly to soil or use as a mulch with germinating seeds.
Coffee grounds show some remarkable properties in suppressing fungal rots and wilts. In studies, the establishment and growth of certain pathogenic fungi and bacteria was prevented. This was the case with cucumbers, spinach, and tomatoes, for example . No studies as yet show conclusive proof of their efficacy in disease suppression on other food crops, trees or shrubs.
Slugs and snails hate coffee grounds, and earthworms adore them! This makes coffee grounds an absolute must-have for any garden. Earthworms eat coffee grounds and then distribute them throughout the soil of your yard and garden in the form of highly nourishing casting of worms. This is one of the best soil amendments ever.
Coffee is an incredibly versatile plant, and coffee grounds are full of nutrients and good stuff even after a good hoy brew. They have other uses for you to consider.
When you use coffee grounds as fertilizer on your yard, you will never have to deal with a manure from organic matter or chemical smell from chemical fertilizers. Additionally, coffee grounds act as a natural cat repellent. If you have had problems with neighbors’ cats (or your own) scratching in your yard, your problem is solved.
When you use coffee grounds to feed your yard, you’ll have beautiful, healthy, lush green plants in a pleasant, inviting setting. You are sure to be proud of your beautiful garden, not to mention being proud of yourself for doing your part to reduce, reuse and recycle.
Composting coffee grounds helps prevent landfill overflow and supports you in creating some healthy, green space to benefit yourself, your family members and friends and local beneficial wildlife.
Coffee grounds can safely makeup to 20% of total compost volume. More than that may be detrimental. Twenty-percent total volume is sufficient for effective disease suppression and for building soil, and should not acidify your soil (pH levels vary according to type of soil, microorganisms present, rainfall, nature of compost and many other factors).
Using coffee grounds alone as a mulch is fine, but don’t lay them on too heavily, as they compact easily and may actually serve to block air and water exchange. It’s best to use coffee grounds in combination with an organic mulch, or layered underneath a mulch like wood chips to avoid compaction.
Coffee grounds will not permanently acidify garden soil as do peat moss or sulfur-based additives; they’ll only affect the acidity in the immediate area. My best recommendation is to add coffee grounds to your compost along with dried, shredded leaves and grass clippings.
Logging in to comment gives you more features, but it is not required.
Look at combinations of plants, colours, textures to match or complement. Use combinations of primary colours; complementary colours; analogous colours
Wild senna is an underrated plant with striking yellow blooms and attractive foliage. It is a host plant for sulphur butterflies.
Learn how to make exquisite chive flower and raspberry vinegars at home with these easy recipes. Perfect for cooking or gifting to friends!
White spruce provides nesting sites, shelter, as well as food for many kinds of wildlife. If you love seeing wildlife, its a good choice.
A listing of local Eastern Ontario events related to sustainable food production including a winery, a herb festival, garlic festivals and a lavender farm.
Quickly learn everything you need to know about composting for your garden, including materials to use, methods and benefits. Easily reduce your environmental footprint and save money on large bags of compost from gardening stores with this user-friendly guide.
When reading the post, you’ll know how to care for winter plants, and what conditions to create to ensure their health and survival in cold seasons. You’ll find practical tips and the list of the best plants to grow in winter in either pots or gardens.
Focus your energy on new skills if your landscaping demands too much of your time. Embrace some low-maintenance landscaping principles.
Eco friendly gardens are gaining popularity. Here's sharing key elements to make your garden eco-friendlier and more sustainable.
Veggie Bites allowed me to share my own trials and tribulations so I could make it easier for other vegetable gardeners.
Discover the refreshing beauty and great ideas of Beth and Ken Powell's private garden featuring remarkable art creations in this photo exhibit.
Discover how to get desert cacti to bloom with the right environment and care. Get tips for providing the perfect environment for desert and holiday cacti, so you’ll be enjoying blossoms all year long. Check out this article to learn how to keep temperatures cool and light intensity high to stimulate blooming.
GardeningCalendar.ca gets some funding from advertisers. If you click on links and advertisements at no cost to you, the site may receive a small commission that helps fund its operation.
© 2025 J&S Calendars Ltd.