Beyond the Brew: Unearthing the Garden and Cleaning Potential of Spent Coffee Grounds and Tea Leaves

Question: What are some ways to repurpose leftover coffee grounds or tea leaves for gardening or household cleaning?

The ritual of brewing coffee or tea often leaves behind a substantial amount of spent grounds and leaves. Far from being mere waste, these organic materials harbor a surprising array of benefits for both the diligent gardener and the eco-conscious housekeeper. With a little knowledge, these common kitchen discards can be transformed into valuable resources.

Nourishing Your Garden with Spent Coffee Grounds and Tea Leaves

Spent coffee grounds are a well-documented boon for soil health. They are a source of nitrogen, phosphorus, and potassium, essential macronutrients for plant growth [1, 7]. When composted, coffee grounds contribute to the creation of nutrient-rich humus, improving soil structure and water retention. Their slightly acidic nature can also benefit acid-loving plants such as blueberries, azaleas, and rhododendrons, though it’s advisable to use them in moderation to avoid significantly altering soil pH [3].

Similarly, used tea leaves, particularly those from black tea, can be a valuable addition to the compost pile. They introduce organic matter and contribute to the nutrient profile of the finished compost. Like coffee grounds, their slightly acidic properties can be beneficial for certain plants. Some studies suggest that coffee processing methods, such as anaerobic fermentation, can influence the chemical composition and quality of the resulting coffee co-products [2, 3, 5], hinting at the diverse organic compounds present in spent grounds.

For direct application to the soil, it’s often recommended to dry the coffee grounds and tea leaves to prevent mold growth. They can then be lightly tilled into the top layer of the soil or added to the base of established plants. Some gardeners have also reported using them to deter pests, though scientific evidence supporting this specific application is less robust. The key is to incorporate them judiciously, allowing their beneficial properties to enhance soil fertility and structure over time.

Harnessing Their Cleaning Power

Beyond the garden, spent coffee grounds offer surprising utility in household cleaning. Their granular texture makes them a mild abrasive, capable of scrubbing away grime without scratching surfaces. A paste made from coffee grounds and a little water can be effective for cleaning greasy pots and pans, or even for de-odoring hands after chopping garlic or onions. The residual oils in the grounds can help lift stubborn residues [1].

Tea leaves, particularly used ones, can also contribute to cleaning efforts. They are known to absorb odors effectively. Placing dried used tea leaves in small sachets in refrigerators or closets can help neutralize unpleasant smells. Furthermore, the tannins present in tea leaves can be useful for cleaning and polishing wooden furniture, providing a subtle sheen. A weak infusion of used tea leaves can be used to wipe down wood surfaces, offering a natural polish.

Research into the composition of coffee grounds has identified various compounds, including cellulose microfibrils, which are being explored for various applications [7]. While these advanced uses are beyond typical household recycling, they underscore the inherent chemical richness of this discarded material. Similarly, studies on coffee processing highlight the diverse volatile compounds present, some of which contribute to the aroma and flavor profiles of the final product [2, 4, 5]. This chemical complexity likely translates to their efficacy in various domestic applications.

In conclusion, the journey from cup to compost or cleaning cloth is a testament to the sustainable potential of everyday kitchen waste. By recognizing the inherent value in spent coffee grounds and tea leaves, we can reduce landfill contributions while simultaneously enriching our gardens and simplifying our cleaning routines with natural, effective solutions. These humble remnants of our daily beverages offer a powerful example of how small changes in habit can lead to significant environmental and practical benefits.

References

[1] — Ernesto Illy, Luciano Navarini — Neglected Food Bubbles: The Espresso Coffee Foam. — 2011-Sep — https://pubmed.ncbi.nlm.nih.gov/21892345/ [2] — Gustavo Galarza, Jorge G Figueroa — Volatile Compound Characterization of Coffee ( — 2022-Mar-21 — https://pubmed.ncbi.nlm.nih.gov/35335365/ [3] — Katarína Poláková, Alica Bobková, Alžbeta Demianová, Marek Bobko, Judita Lidiková, Lukáš Jurčaga, Ľubomír Belej, Andrea Mesárošová, Melina Korčok, Tomáš Tóth — Quality Attributes and Sensory Acceptance of Different Botanical Coffee Co-Products. — 2023-Jul-11 — https://pubmed.ncbi.nlm.nih.gov/37509767/ [4] — Rongsuo Hu, Fei Xu, Liyan Zhao, Wenjiang Dong, Xingyuan Xiao, Xiao Chen — Comparative Evaluation of Flavor and Sensory Quality of Coffee Pulp Wines. — 2024-Jun-27 — https://pubmed.ncbi.nlm.nih.gov/38999011/ [5] — Faguang Hu, Haohao Yu, Xingfei Fu, Zhongxian Li, Wenjiang Dong, Guiping Li, Yanan Li, Yaqi Li, Bingqing Qu, Xiaofei Bi — Characterization of volatile compounds and microbial diversity of Arabica coffee in honey processing method based on different mucilage retention treatments. — 2025-Jan — https://pubmed.ncbi.nlm.nih.gov/39974542/ [6] — Jaquellyne B M D Silva, Mayara T P Paiva, Henrique F Fuzinato, Nathalia Silvestre, Marta T Benassi, Suzana Mali — An Ultrasonication-Assisted Green Process for Simultaneous Production of a Bioactive Compound-Rich Extract and a Multifunctional Fibrous Ingredient from Spent Coffee Grounds. — 2025-Jul-25 — https://pubmed.ncbi.nlm.nih.gov/40807293/ [7] — Hitoshi Soyama, Kousuke Hiromori, Naomi Shibasaki-Kitakawa — Simultaneous extraction of caffeic acid and production of cellulose microfibrils from coffee grounds using hydrodynamic cavitation in a Venturi tube. — 2025-Jul — https://pubmed.ncbi.nlm.nih.gov/40288159/