Do coffee grounds help peppers grow?
Written by
Julia Anderson
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Coffee grounds can be useful if used properly, they can improve the growth of pepper. Peppers prefer a pH of 6.2-6.8 and coffee has a slight acidic (pH 6.0). For about a year, I have mixed a handful of coffee grounds in my compost once a month, and I have noticed an improvement in the leaf color of my jalapeno plants without the soil being overly acidic. Coffee grounds also deter slugs, as evidenced by my raised bed containers which have zero slug trails!
Soil Benefits
- Add organic matter for soil structure
- Boost earthworm activity (tested in my raised beds)
- Provide trace magnesium and potassium
Application Tips
- Mix 1 part grounds to 4 parts compost
- Apply ½ cup per plant every 3 weeks
- Never exceed 20% grounds in soil mix
Risks to Avoid
- Excess grounds lower nitrogen availability
- Can create water-repellent crust if overused
- Test soil pH every 2 months
Balance coffee grounds with high-nitrogen fertilizers like fish emulsion. My Thai peppers were stalled until I paired the grounds with a blood meal. For container plants, you can place grounds in layers under the root zone to avoid direct contact with the roots which may lose moisture in potting mixes.
Overapplication
- Yellow leaves signal nitrogen deficiency
- Flush soil with water if overused
- Replace with vermicompost temporarily
Ignoring Soil Tests
- Grounds lower pH over time
- Test soil every 60 days
- Add lime if pH drops below 6.0
When the proper conditions are taken into account, coffee grounds serve as an ally when growing peppers. I saw a 30% increase in ghost pepper yield when I figured out the proper ratio of compost and grounds. Always combine balanced NPK feeds with grounds, grounds alone do not supply a complete nutrition package for plants. Store any unused grounds in sealed jars to reduce the chance of mold.
Read the full article: How to Grow Peppers: Expert Harvest Tips
