Coffee Grounds & Pepper Plants

Coffee grinds make a nice compost for pepper plants.
Coffee grinds make a nice compost for pepper plants. (Image: Jupiterimages/ Images)

Every time you prepare to start your day with a pot of fresh coffee, you are brewing a valuable gardening addition. Leftover coffee grounds contain multiple nutrients that make excellent supplements for growing vegetables, including pepper plants, according to Washington State University. However, preparing and applying coffee grounds properly is a key component to complimenting pepper plant growth.

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Coffee Grounds Facts

Coffee grounds are a nutrient-rich growing medium. The grounds contain more than 10-percent nitrogen. When composted, they have a 10-to-1 carbon-to-nitrogen ratio, a good mixture to facilitate healthy plant growth, according to Washington State University. In addition, several anti-microbial chemicals such as hydrophobic lipids, essential oils, cholesterols and fibers remain in the grounds after brewing. These components can help reduce soil-borne microbes and pests that damage pepper plants in your garden.


Coffee grounds help prevent pathogenic bacteria and fungi from damaging pepper plants when used as an ingredient in a composting mixture. Coffee grounds also increase soil fertility and help acidify soil pH. Like most composting materials, coffee grounds help maintain soil moisture, improve soil drainage and protect pepper plant roots from extreme temperature changes in home gardens.


Coffee grounds can be problematic when used alone as a composting or mulching medium for pepper plants. The small grains of coffee grounds are easily compacted. When coffee grounds are saturated and then allowed to dry, they often develop a hard, cake-like texture that inhibits air flow as well as water flow from the soil surface and can reduce pepper plant vitality.

Best Use

Coffee grounds are best used as an ingredient in a well-balanced composting formula for pepper plants. A small percentage of coffee grounds in a composing mixture still provides the anti-microbial benefits without the risk of compaction and root suffocation, according to Washington State University. If you use coffee grounds as a pure mulch, apply no more than a 1/2-inch layer around your pepper plants.


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