Answer: Coffee grounds do increase soil acidity. Neither tea leaves nor coffee grounds, in moderate amounts, will harm your azaleas or other acid loving plants. However, an excess of any single element can disrupt the natural balance. Why not add the coffee and tea directly to your compost pile instead, and then add the complete organic compost material to your azalea as a mulch? If your soil is still in need of additional acidity, add sulfur to the compost mulch.
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