I Sprinkle the Soil Around the Hydrangeas With This. The Flowers Bloom Like Crazy, They Are Bigger and Hold Their Color Longer

Hydrangeas produce abundant, ball-shaped flowers ranging in color from red through various shades of pink to white. In the right soil, they produce blue or lavender-blue flowers. Coffee grounds are one way to create the right conditions for this.

Coffee grounds acidify the soil, making hydrangea flowers blue rather than the typical pink or white. The acidity of the grounds is key, although aluminum sulfate or eggshells will give you the same effect. All hydrangea flowers respond to increased acidity in the soil, although the soil must still be fertile and well drained.

To measure the acidity of your soil, use a soil test kit, which can be purchased at any garden or home improvement store. To increase the acidity of the soil, enrich it with coffee grounds by digging them into the soil. Laying coffee grounds on top of the soil is faster, but can result in an ugly pile of mold that looks messy and smells bad.

Changing the color of flowers to blue with coffee grounds is not always a quick process. Some hydrangeas produce flowers on last year's growth, others on this year's growth. Flower buds usually begin to develop on hydrangeas that are two or three years old, depending on the species and variety. The buds develop in winter and continue to develop in spring, producing full flowers in late summer or early fall. As a result, the earlier you add coffee grounds to the soil, the earlier you will affect the color of the hydrangea's blooms.

Coffee grounds also help retain moisture in the soil, which is an added benefit for your hydrangeas. They grow best with a strong weekly watering, and coffee grounds help keep the soil moist in the meantime. In addition to hydrangeas, coffee grounds also promote the growth of other plants, especially azaleas and rhododendrons.

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