| Is it possible to change a light blue to a darker blue on a hydrangea? Thanks! |
| Hydrangea color is somewhat genetic but soil pH can also affect the color. While your soil is naturally acidic, which is what makes a hydrangea blue, you may be able to acidify it a little more to get a darker blue color. Treat the soil with 2 Tablespoons of aluminum sulphate per plant, making 4-6 applications at 2 week intervals, starting in the early spring before the plants bloom. (Sulfur will acidify the soil. The desired pH range would be between 5.5 and 6.) |
