Overview

• Hydrangea bloom color is determined by soil pH, with acidic soil (pH 5.5 or lower) producing blue flowers due to increased aluminum availability.
• Coffee grounds are a simple, eco-friendly method to lower soil pH, making aluminum more accessible to hydrangeas for blue blooms.
• Experts recommend routine pH testing, monthly applications of coffee grounds, and avoiding direct contact with plant stems for best results.
• Adding aluminum sulfate can accelerate the transformation, though coffee grounds alone are effective with time and consistency.
• Pre-composting coffee grounds enriches soil health, providing additional nutrients and aligning with sustainable gardening practices.