Controlling Bloom Color on Big Leaf Hydrangeas

The color of your big leaf hydrangeas can be controlled to a certain extent by controlling the soil’s acidity, or PH. A soil PH below 5.5 encourages the bluest flowers, while a soil PH of 6.5 or higher encourages pink to red flowers. Use aluminum sulfate to lower the PH and lime to increase the PH. Apply 4 tablespoons of the aluminum sulfate mixed with a gallon of water around the plant in early spring for blue blossoms. Repeat again in about 3 weeks. Lime or applying superphosphate in quantity may be added to the soil in spring and fall and spread around the base of plants to deepen the color of pink and red blossoms. It may take one year for the results to be seen. The only way to be sure of your PH to start with is to have a soil test done, however, most of us in this area have an acidic soil which makes our flowers blue without adding anything to the soil. White Hydrangeas are not affected by soil PH. We have the products needed to change your PH in our gift shop.