Sustainable gardening practices are becoming crucial, and for coffee enthusiasts with a green thumb, using coffee grounds for plants and crops offers a great opportunity. These grounds are more than waste and make a valuable addition to your garden, boosting plant growth while enhancing your soil’s health.
You can use coffee grounds for gardening to enrich soil with nitrogen, enhance soil structure, and act as a natural fertilizer for its micro-nutrient content. However, you’ll want to avoid applying too many grounds to prevent adverse effects on plant growth.
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Today, you will easily learn how to incorporate coffee grounds into your garden and several vital strategies to avoid common problems such as mold growth and to keep your soil from retaining too much moisture. I will also provide a simple step-by-step method for using coffee grounds as fertilizer and identify which plants benefit most and which plants to avoid using coffee grounds on. Let’s go!
- Discover these 3 key ways you can use coffee grounds in your garden to grow healthier and more productive plants PLUS 5 methods to apply spent grounds in your green space today!
- Save time with this done-for-you 8-step process for composting used coffee grounds in your backyard composting pile or tumbler so you can reduce household waste and be a sustainable gardener.
- Stop guessing and save money by knowing which plants enjoy coffee grounds and which don’t, so you’ll know where to apply them and how to get the most out of your green friends!
Uses Of Coffee Grounds For Plant Food
Coffee Ground For Nitrogen-Fixing
Coffee grounds can be added to soil as a slow-release fertilizer that provides plants with a steady source of nutrients, including nitrogen, which promotes greener foliage. Although coffee grounds are just one alternative in providing and improving fertile and nutrient-dense garden soil, they can also be a great source of phosphorus to your garden’s soil. Phosphorus is an essential element that plants need in large quantities to convert sunlight into energy. 1
Micro-Nutrients In Coffee Grounds
Coffee grounds contain several micronutrients, including magnesium, sodium, iron, copper, and manganese, which are essential for plant enzymes and stress tolerance. Stress tolerance is a plant’s capacity to withstand environmental challenges like drought, temperature changes, and nutrient deficiencies.
Micronutrients are required in minimal amounts, typically less than 1% of a plant’s overall nutrient intake. However, even in small quantities, their deficiency can cause issues such as stunted growth and chlorosis (pale green color), potentially resulting in plant death if not corrected.
That is why it’s crucial to apply them in moderation to avoid nutrient imbalances, which means using them sparingly and not exceeding what is necessary for healthy plant growth.
Using Coffee Grounds As Natural Pest Deterrent
Coffee grounds can also be used effectively to deter troublesome garden pests. Sprinkle them around the base of plants to help keep ants, snails, and slugs away. The coarse and gritty texture of the grounds creates a barrier, making it uncomfortable or difficult for slimy critters such as snails and slugs to cross. 2
Also, keep your garden clean by clearing leaves and other places where pests might hide. Clearing ground debris helps make coffee grounds even better at keeping pests away.
Best Ways To Use Coffee Grounds As Fertilizer
Spread Directly Onto The Soil
Spread coffee grounds directly onto the soil or sprinkle a thin layer around the plant base to protect against weeds. By doing so, coffee grounds can improve soil structure and aeration, making it easier for plant roots to access water and nutrients.
Integrate Into Your Mulch
Coffee grounds and water can also be mixed into the soil as mulch to help regulate moisture. To do this, you can place them in a container and then add water. Stir until thoroughly soaked, then spread it around the base of your garden beds. 3
Make A Liquid Fertilizer
Create a liquid solution by mixing the grounds and water in a sprayer. Lightly spray the mixture on the leaves using a teaspoon of coffee grounds per gallon of water. This method deters pests and serves as a potential natural herbicide, inhibiting seed germination as observed in research conducted by the Federal University of Rio Grande do Sul. 4
Add It To Your Seed-Starting Mix
Coffee grounds add the best nitrogen source for your seed-starting mix, providing a good kick-start for your seedlings for healthy development and initial root growth. Mix the grounds and seed mix and wait for the seedlings to flourish.
Mix With Other Compost Materials
An ideal balance involves mixing coffee grounds into your compost with other natural materials, such as leaves or carbon-rich substances (brown compost). Some common brown materials are dry leaves, shredded newspaper, cardboard (cut into small pieces), straw or hay, and sawdust (from untreated wood). Remember, it’s crucial not to exceed a 20% ratio of coffee in the total compost volume.
Consider using coffee grounds that have been brewed, as they are generally used in gardening. If you are planning to use fresh grounds that have yet to be used to brew coffee, it’s suggested to dry them first. Below, we’ll walk through a simple step-by-step method of adding coffee grounds to your compost pile to enhance your compost and, ultimately, your garden when applied.
Tossing coffee grounds into your compost bin is an excellent way to help reduce household waste and provide nutrients to your flourishing garden. However, check out this informative video below to see how to do it for yourself – PLUS some additional insider information to help your plants stand out and produce more!
Steps In Composting Coffee Grounds As Fertilizer
Step 1: Gather Coffee Grounds
Collect coffee grounds and any paper coffee filters you have, as coffee filters are usually biodegradable and naturally decompose. Tear the filters into smaller pieces before incorporating them into the compost.
Step 2. Balance With Other Materials
Coffee grounds are considered “green” compost materials because they are nitrogen-rich. To balance your compost, mix coffee grounds with “brown” materials like dry leaves, shredded newspaper, or cardboard, which are high in carbon.
Aim for a balanced carbon-to-nitrogen ratio to promote decomposition, typically consisting of a 3:1 ratio of browns (carbon) to greens (nitrogen). 5
Step 3. Layer In The Compost Bin
When you toss your used dregs (residue left at the bottom of a coffee cup) into the compost bin, spread them out evenly with other composting materials. This incorporation helps air penetrate your pile and prevents your heap from compacting, stopping the natural decomposition process.
Step 4. Avoid Clumping
Keep the coffee grounds from sticking together in big clumps since they can block the air in the pile. Mix them well to prevent this from happening so they spread out evenly.
Step 5. Put Coffee Grounds In Moderation
While used and fresh grounds are excellent, avoid putting too much in your compost at once, as a thin layer with each addition is sufficient. However, you can add them regularly to your compost mixture if necessary.
Step 6. Monitor Moisture Levels
While moisture is vital in your compost, your compost pile shouldn’t become waterlogged. Used grounds have a high moisture content, so be mindful of the overall levels and adjust accordingly by increasing dry materials if needed. 6
Step 7. Turn The Pile Regularly
Regularly turn or mix your compost pile at least once weekly to improve aeration and expedite decomposition. Although this mixing aids in the even distribution of materials keep in mind that composting requires time, so practice patience.
Step 8. Harvest The Finished Product
Once your compost has decomposed into a dark, crumbly material with a rich, earthy smell, it has matured (humus) and is ready to be used and spread within your garden. Apply the humus around the base of your plants to boost nourishment and sustain healthy growth, or apply a few inches of it in the fall and spring.
Disadvantages Of Using Coffee Grounds In The Garden
While coffee grounds on plants have several benefits, here are the potential cons of using coffee grounds excessively.
Damage To pH-Sensitive Plants
Some plants are sensitive to changes in pH, such as lettuce, basil, cilantro, lemon balm, and grapes. Applying coffee grounds into the soil and near pH-sensitive plants can lead to imbalances and negatively impact their growth.
However, using them liberally can make the soil too acidic, harming the good bacteria and earthworms that help the earth stay healthy, fertile, and ripe for excellent plant and crop production. 7
Coffee grounds are high in moisture and can cause mold to grow, especially if you tend to overwater your garden beds. To avoid this, use the grounds sparingly and avoid adding multiple layers to your garden.
Excess Moisture In The Soil
Coffee grounds retain moisture, which can be problematic if not managed properly. In areas with high moisture levels, this can result in excessive water retention in the soil.
Plants That Like Coffee Grounds In Your Garden And Those That Don’t
Which Plants Like Coffee Grounds Most
Plants such as azaleas, camellias, hydrangeas, gardenias, thyme, rosemary, parsley, chives, mint, potatoes, radishes, corn, cabbage, cucumbers, turnips, kale, blueberries, cranberries, strawberries, raspberries, blackberries, pineberries, and apples benefit from coffee grounds as compost for several reasons:
- Coffee grounds are slightly acidic, which makes them suitable for acid-loving plants such as azaleas, camellias, hydrangeas, and blueberries.
- They add organic matter to the soil, improving its structure, water retention, and aeration, which many plants, including vegetables like potatoes and corn, find favorable.
- Worms are often attracted to coffee grounds, and their presence can enhance soil quality through their natural digging and fertilizing activities.
Which Plants Do Not Like Coffee Grounds In Gardens
Plants such as lilacs, daffodils, iris, snapdragons, yarrow, lettuce, basil, cilantro, lemon balm, chervil, tarragon, asparagus, celery, artichokes, beets, grapes, figs, and pomegranates generally do not appreciate coffee grounds in garden for the following reasons:
- These plants prefer neutral to alkaline soil.
- Coffee grounds contain phosphorus, which is essential for root development and flowering. Plants primarily focusing on leafy growth may require less phosphorus than basil, cilantro, and lettuce.
- Since coffee grounds retain moisture, this might not be suitable for plants that prefer well-draining soil. Examples are daffodils and iris. 8
Neutral Plant Options
These plants typically have a broad pH tolerance range and are relatively unaffected by the acidity of coffee residues. Such plant varieties encompass marigolds, zinnias, sunflowers, nasturtiums, lavender, sage, daisies, peppers, tomato plants, and cucumbers.
These plants also have a high degree of adaptability and can thrive in soils with various pH levels, whether slightly acidic, neutral, or slightly alkaline. They are versatile and resilient that way.
Coffee grounds are a fantastic option for sustainable gardening and natural fertilization. They provide essential nutrients like nitrogen and phosphorus, which enhance soil quality and promote eco-friendly gardening practices. However, maintaining a balance in their use is crucial to prevent potential issues like soil acidification, mold growth, and excessive moisture.
By incorporating coffee grounds gradually, you can create a beneficial treat for your plants while seamlessly integrating them into your garden’s soil. This practice benefits your garden and reduces waste by repurposing a resource that would have otherwise ended up in the trash.
Coffee grounds become a treat for your plants when added gradually, seamlessly blending with the soil. It is one way of using something that would have ended up in the trash. So, make coffee, relish the aroma, and watch your plants thrive with the perks of your coffee habit.
Do you currently add coffee grounds to your green space or compost with success? We’d love to hear about your method of recycling. Drop us a line in the comment section below to share your process with your fellow gardeners!
- National Library Of Medicine, National Center For Biotechnology Information – Chemical Properties Of The Coffee Grounds And Poultry Eggshells Mixture In Terms Of Soil Improver
- University Of Arizona, Cooperative Extension – Using Coffee Grounds In The Garden
- University Of Connecticut, College Of Agriculture, Health, And Natural Resources – Using Coffee Grounds In Your Garden
- National Library Of Medicine, National Center For Biotechnology Information – Temperature Requirements For Seed Germination Of Pereskia Aculeata And Pereskia Grandifolia
- ScienceDirect – Spent Coffee Grounds By-Products And The Influence On Soil C-N Dynamics
- ResearchGate – Using Coffee Grounds In Gardens And Landscapes
- Oregon State University, Extension Service – Used Appropriately, Coffee Grounds Improve Soil And Kill Slugs
- MDPI – Spent Coffee Grounds Applied As A Top-Dressing Or Incorporated In The Soil Can Improve Plant Growth While Reducing Slug Herbivory