Here’s something to buzz about: Using coffee grounds to enrich houseplants can be a win-win. First, recycling this widespread by-product of caffeine consumption means a little less waste ends up in the landfill. Secondly, coffee grounds can improve soil quality and act as a fertilizer for some plants. To learn more about it, we tapped two expert sources: Christopher Griffin, aka @plantkween, a Brooklyn-based plant educator, author, and influencer who is currently caring for over 200 plants in their apartment; and Amelia Rosser, proprietor of Sheelytown Market, a sustainable plant and local goods shop in Omaha, Nebraska. Read on for their insider tips on how to best use coffee grounds for your houseplants.
Why Do Coffee Grounds Help House Plants?
According to Griffin, used coffee grounds are high in nitrogen. This nutrient is essential to help plants produce chlorophyll and grow into happy, healthy companions. And, because used coffee grounds are readily available in many homes, they provide a free option for fertilizer.
What Type of Plants Benefit from Coffee Grounds?
Coffee grounds fertilizer is not the answer to all your plants’ needs. But some plants really do love this sustainable method. Griffin shares that their list of coffee-grounds-friendly “green gurls” includes roses, azaleas, blueberries, tomatoes, hydrangeas, ferns, peonies, African violets, rhododendrons, and camellias.
The color of hydrangeas can be influenced by soil pH, and coffee grounds can help to lower the pH, which promotes vibrant blue or purple blooms.
Plant shop boss Rosser cautions that “not all plants thrive with coffee grounds, so research your specific plant’s preferences before using them.” But, she says, “Some plants do appreciate the presence of coffee grounds in their soil. Hydrangeas are a prime example.” The color of hydrangeas can be influenced by soil pH, and coffee grounds can help to lower the pH, which promotes those vibrant blue or purple hues in their blooms.
The plant pro adds, “Other acid-loving plants like azaleas, rhododendrons, and blueberries can also benefit from the slight acidity provided by coffee grounds. Just remember to use coffee grounds in moderation to avoid overacidifying the soil.”
How to Use Coffee Grounds on House Plants
There are two basic methods for using coffee grounds on houseplants: mixing grounds into the soil or diluting them with water to form liquid fertilizer. Griffin tends just to mix coffee grounds into the soil “and let the gradual nutritious magic happen.” Please note that if using this method, the mixing is critical, as just sprinkling used grounds on top of a layer of soil is less effective and can create a barrier to water and other nutrients reaching your plant.
Ferns can also benefit from coffee grounds.
Another viable option is to create liquid fertilizer from coffee grounds. (We promise, it’s simpler than it sounds.) In a gallon of water, dilute roughly a teaspoon of coffee grounds. Let this mixture steep for a couple of nights, stirring occasionally. Strain that liquid using a cheesecloth or fine mesh strainer. Then, use the potion to water your houseplants while also gently fertilizing them. Remember: Less is more when it comes to coffee grounds love for your plants.
What to Watch Out For
It can be easy to misuse coffee grounds. Rosser explains that using them on houseplants can be a bit tricky. “While coffee grounds do contain micronutrients that can benefit plants, the average coffee consumer might produce too many for them to be a sole source of fertilizer.” Coffee grounds use must be done in moderation since the potential downside is that the acidity of the grounds can contribute to overly acidic soil. “[This] may lead to root rot in some plants,” according to the Sheelytown Market owner.
Additionally, influencer Griffin wants plant parents to remember that houseplants have a concoction of nutrients that they enjoy. For example, “While used coffee grounds are high in nitrogen, they are relatively low in potassium and phosphorus,” they explain.
The bottom line is that a balanced approach to plant care is the winning ticket. “While coffee grounds can be beneficial, it’s important to incorporate a well-rounded approach to plant care, including appropriate watering, sunlight, and a balanced fertilizer regimen,” Rosser advises.
