Don't Throw Away Coffee Grounds: Gardener Reveals How They Can Help Hydrangeas

Gardeners seeking to achieve lush, vibrant hydrangeas may find a surprising ally in their kitchen: used coffee grounds. A gardener named Brittany, who shares nature-friendly gardening tips on TikTok, has highlighted how this common household waste can significantly benefit popular garden shrubs.

According to Brittany's experience, hydrangeas treated with coffee grounds developed larger flowers and a more intense blue hue compared to those that did not receive this treatment. This effect is primarily attributed to the coffee grounds' ability to lower soil pH, making the soil more acidic. Hydrangeas, particularly mophead and lacecap varieties, are known to change flower color based on soil acidity, with lower pH levels promoting blue coloration.

To use coffee grounds, a small amount can be spread around the base of the plant. It is then recommended to water the area to help the grounds integrate into the soil. This method is most effective for purple and blue hydrangeas, helping to deepen and maintain their rich shades.

However, the impact of coffee grounds varies among hydrangea types. White hydrangeas, for instance, do not change color based on soil pH, so adding coffee grounds will not turn their blooms blue. Similarly, varieties like 'Limelight' naturally transition through various colors and are not affected by soil acidity in terms of their fundamental color. The final appearance of hydrangea blooms is influenced by a combination of factors, including the specific variety, soil pH, soil composition, and the availability of aluminum in the soil.