How to turn Hydrangeas blue
Using a soil test kit, check the PH level of the soil. You can buy a soil testing kit from a local garden centre or hardware store.
For blue hydrangeas, the soil should be acidic and have a pH level between 4.5 and 5.5. To increase the acidity of the soil, add iron sulfate or a soil acidifier near the base of the plant.
How to turn hydrangeas pink
On the other hand, if you want your hydrangeas to be pink, you'll need to raise the PH level. According to www.bhg.com, "To raise the pH of acid soil, add ground limestone from a local garden centre or hardware store, or wood ashes from a fireplace or stove (this is called 'sweetening the soil')."
Have you tried this? Tell us about it in the comments.
RELATED: Three tricks for hydrangeas