Are you a coffee lover looking for a way to boost your garden? Don’t toss those used coffee grounds in the trash! Instead, sprinkle them around your acid-loving plants for a natural fertilizer to make them thrive.
Studies have shown that coffee grounds can improve soil structure and water retention and provide essential nutrients like nitrogen, potassium, and phosphorus.¹
Here are 18 plants that will love the extra acidity your leftover coffee provides.
1. Azaleas
Azaleas are stunning flowering shrubs that bloom in a rainbow of colors each spring. To keep their soil slightly acidic, which azaleas prefer, sprinkle a thin layer of used coffee grounds around the base of the plant.
As they decompose, the grounds will also boost the soil with nutrients like nitrogen and potassium.
Be careful not to overdo it, though—a half-inch layer of ground is plenty. Applying a too-thick layer can repel water and reduce airflow to the roots.
2. Blueberries
Blueberries are one of the most beloved acid-loving fruits. These antioxidant-packed berries require highly acidic soil to produce an abundant harvest. Coffee grounds are the perfect natural amendment to maintain that acidity.
When planting new blueberry bushes, mix used coffee grounds into the soil. For established plants, lightly scatter the grounds on the soil surface and cover them with mulch.
The coffee will not only acidify the soil but also provide a slow-release source of nitrogen that blueberries crave.
3. Hydrangeas
Hydrangeas are famous for their ability to change flower color based on soil pH. If you dream of vibrant blue hydrangea blooms, used coffee grounds can help you achieve that goal. Coffee grounds are slightly acidic, encouraging hydrangeas to produce blue flowers instead of pink.
Work a moderate amount of ground into the soil around your hydrangeas each spring. Coffee grounds can also help improve soil structure and water retention.
Remember that hydrangeas are sensitive to fertilizer burn, so don’t go overboard.
4. Rhododendrons
Rhododendrons, close cousins of azaleas, are another group of acid-loving shrubs. These evergreen plants boast clusters of showy blooms in the spring and thrive in shady woodland settings.
Like azaleas, they grow best in soil with a pH between 4.5 and 6.01.
To maintain that acidity, apply a half-inch layer of used coffee grounds around the base of your rhododendrons once a month during the growing season. The grounds will slowly acidify the soil as it breaks down while suppressing weeds and improving moisture retention.
5. Camellias
Camellias are elegant evergreen shrubs that bloom in late winter and early spring, providing a welcome pop of color when most plants are dormant. These acid-loving plants prefer a pH between 5.0 and 6.5, making coffee grounds an ideal amendment.
Spread a half-inch layer of used coffee grounds around your camellias every 4-6 weeks during the growing season. The grounds will help maintain soil acidity, add nutrients, and improve soil structure.
Just be sure to keep the grounds away from the base of the plant to avoid stem rot.
6. Gardenias
Gardenias are prized for their intoxicatingly fragrant white flowers and glossy evergreen leaves. However, these beautiful shrubs can be demanding, requiring particular soil conditions to thrive.
Gardenias need acidic soil with a pH between 5.0 and 6.0 and plenty of nutrients.
Used coffee grounds can help create the perfect environment for gardenias. Work a generous amount of grounds into the soil before planting, and apply a half-inch layer around established plants every month during the growing season.
The coffee will acidify the soil, add nitrogen and other nutrients, and improve drainage.
7. Ferns
Many varieties of ferns, such as sword ferns and autumn ferns, thrive in slightly acidic soil. These shade-loving plants are perfect for woodland gardens or as understory plants beneath larger shrubs and trees.
Coffee grounds can help create the ideal soil conditions for these lush, green beauties.
When planting new ferns, mix a handful of used coffee grounds into the soil. For established plants, sprinkle a thin layer of ground around the base of the ferns every few weeks during the growing season.
The coffee will help maintain soil acidity and add nutrients, promoting healthy growth.
8. African Violets
African violets are charming houseplants that produce clusters of colorful flowers above fuzzy, dark green leaves. These compact plants prefer slightly acidic soil and can benefit from the nutrients in coffee grounds.
Mix a tablespoon of dried, used grounds into the potting soil to use coffee grounds for your African violets. You can also steep used grounds in water overnight to create a weak “coffee tea” fertilizer.
Water your violets with the strained liquid once a month to provide a gentle nutrient boost.
9. Radishes
Radishes are one of the fastest-growing vegetables, making them a great choice for impatient gardeners. These spicy root crops prefer loose, slightly acidic soil and can benefit from adding coffee grounds.
Before planting radish seeds, mix a generous amount of used coffee grounds into the top few inches of soil. The grounds will help acidify the soil, improve drainage, and add slow-release nutrients.
Just be sure not to add too much, as an overabundance of nitrogen can cause radishes to produce more leaves than roots.
10. Carrots
Like radishes, carrots are root vegetables that thrive in loose, slightly acidic soil. Coffee grounds can help create the perfect growing environment for these crunchy, nutritious veggies.
Work a layer of used coffee grounds into the soil before planting carrot seeds. The grounds will improve soil structure, add nutrients, and help maintain the slightly acidic pH that carrots prefer.
As a bonus, the coarse texture of the grounds may also help deter pests like carrot rust flies.
11. Roses
Roses are beloved for their stunning flowers and intoxicating fragrance, but they can be challenging to grow. These classic garden plants prefer slightly acidic soil and require plenty of nutrients to produce abundant blooms.
Fortunately, coffee grounds can help meet both of these needs.
Sprinkle a half-inch layer of used coffee grounds around the base of your rose bushes every month during the growing season. The grounds will slowly acidify the soil as it decomposes, adding nitrogen, potassium, and other essential nutrients.
To prevent stem rot, keep the grounds a few inches away from the base of the plant.
12. Tomatoes
Tomatoes are one of the most popular garden vegetables, prized for their juicy, flavorful fruits. While tomatoes can tolerate a wide range of soil pH levels, they perform best in slightly acidic soil with a pH between 6.0 and 6.8.
Coffee grounds can help maintain that ideal acidity.
Mix a generous amount of used coffee grounds into the soil before planting tomatoes. The grounds will improve soil structure, add slow-release nutrients, and help maintain the slightly acidic pH that tomatoes prefer.
Just be sure not to add too much, as an overabundance of nitrogen can cause tomato plants to produce lush foliage at the expense of fruit.
13. Potatoes
Potatoes are starchy, filling root vegetables that are a staple in many cuisines worldwide. These underground tubers prefer slightly acidic soil with a pH between 5.5 and 6.5, making coffee grounds a useful amendment.
Before planting potato tubers, work a layer of used coffee grounds into the soil. The grounds will help acidify the soil, improve drainage, and add slow-release nutrients as they decompose.
Just be sure not to add too much, as an excess of nitrogen can cause potato plants to produce more foliage than tubers.
14. Strawberries
Strawberries are sweet, juicy fruits that are a favorite of gardeners and farmers market shoppers alike. These low-growing plants prefer slightly acidic soil with a pH between 5.5 and 6.5, and they benefit from adding organic matter like coffee grounds1.
Mix a generous amount of used coffee grounds into the soil before planting strawberries. The grounds will acidify the soil, improve soil structure, and provide a slow-release source of nutrients.
You can also sprinkle a thin layer of ground around established plants every few weeks during the growing season.
15. Lily of the Valley
Lily of the valley is a charming woodland plant that produces delicate, bell-shaped white flowers in the spring. This shade-loving perennial prefers slightly acidic soil and can benefit from adding coffee grounds.
Work a layer of used coffee grounds into the soil before planting lily of the valley. The grounds will help maintain the slightly acidic pH that this plant prefers while improving soil structure and adding nutrients.
You can also sprinkle a thin layer of ground around established plants every few weeks during the growing season.
16. Daffodils
Daffodils are cheerful spring-blooming bulbs with sunny yellow flowers that signal the end of winter. These hardy plants prefer well-draining, slightly acidic soil and can benefit from adding coffee grounds.
Before planting daffodil bulbs in the fall, mix a generous amount of used coffee grounds into the soil. The grounds will improve drainage, add nutrients, and help maintain the slightly acidic pH that daffodils prefer.
You can also sprinkle a thin layer of ground around established plants in the spring to boost their nutrient intake.
17. Magnolias
Magnolias are stunning flowering trees that produce large, showy blooms in white, pink, and purple shades. These elegant trees prefer slightly acidic soil and can benefit from adding coffee grounds.
Spread a half-inch layer of used coffee grounds around the base of your magnolia tree every few months. The grounds will slowly acidify the soil as it decomposes, adding nutrients and improving soil structure.
Keep the grounds a few inches away from the trunk to prevent rot.
18. Hollies
Hollies are evergreen shrubs and trees prized for their glossy leaves and bright red berries. These festive plants prefer slightly acidic soil and can benefit from the nutrients in coffee grounds.
Mix a generous amount of used coffee grounds into the soil before planting hollies. For established plants, sprinkle a half-inch layer of ground around the base every few months. The coffee will help maintain soil acidity, add nutrients, and improve soil structure.
Just be sure not to overdo it, as excess coffee grounds can lead to nutrient imbalances.
Source:
Read Next:
Nancy has been a plant person from an early age. That interest blossomed into a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Nancy worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.