The correct answer lies somewhere in between: coffee grounds can be beneficial to roses if used correctly.
The grounds also have antioxidant and antimicrobial properties.
As they break down in the soil, they can suppress plant diseases such as the fungus Fusarium wilt.
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Rosesdo best in slightly acidic soil with a pH between 6.0 and 6.5.
Should I Water Roses with Leftover Coffee?
With a pH of 5.5, brewed, liquid coffee is ten times more acidic than used coffee grounds.
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Adding the coffee grounds directly has more limitations.
Although coffee grounds contain nitrogen, it is not yet in a form that is available to your roses.
Thats why it needs to go through the decomposition process first.
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Rain or irrigation water will simply run off while your roses remain thirsty.
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Coffee Grounds vs.
The only exceptions are roses that grow in the wild and dont need fertilization.
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Rasa Petreikiene / Getty Images
Coffee Grounds - Will They Perk up Plants?Washington State University.
Wake up and Use the Coffee - Grounds, That Is!University of California.
