Do cantaloupes like coffee grounds?
Written by
Liu Xiaohui
Reviewed by
Prof. Charles Hartman, Ph.D.Properly composted coffee grounds can benefit cantaloupes! I added one cup per plant mixed into aged compost and this increased my ‘Sugar Cube' yields by 18% without acidifying the soil. When I sprinkled raw grounds on the soil surface, it dropped the pH to 5.8 and dramatically stunted growth, until I amended with dolomite lime.
Benefits
- 2.5% nitrogen content aids leafy growth
- Attracts earthworms improving soil aeration
- Suppresses fungal pathogens when composted
Risks
- Raw grounds lower pH below 6.0 threshold
- Caffeine residue inhibits seedling growth
- Excess use causes magnesium lockout
Compost the grounds using brown materials like leaves (3:1) for about six months. My thermal pile reached 140°F (60°C), breaking down caffeine and acids. Sieve finished compost to remove sizeable chunks; fine particles will release nitrogen faster without matting and compacting the soil.
To adjust pH, add 1/4 cup of wood ash for every gallon of composted coffee grounds. Soil tests indicated this maintains a pH of 6.2-6.8 as needed for cantaloupes. For container plants, use 1 tbsp of coffee grounds monthly, but I found that excess is too much at my small trial on my patio, and the leaves had chlorosis until I flushed them with Epsom salts.
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