Ever wonder why these big, beautiful flowers seem to spontaneously bloom pink or blue? Their color is actually a result of the pH (acidity or basicity) of their planting soil!
NOTE: If you are already feeling your eyes begin to glaze over at the mention of chemistry terms, please just scroll down and simply enjoy the beautiful shots of hydrangeas I took during my walk to the Post Office this week and ignore the text :)
So how does this work?
In more basic soil (above pH = 5.5), aluminum ions (which are toxic to most other plants) are bound to other ions like oxygen and phosphate in the soil, the hydrangea is unable to take up the aluminium and more pink-colored blooms are observed. In more acidic soil (below pH = 5.5), the aluminum ions roam free within the soil and are able to be more easily absorbed by the hydrangea roots. Once absorbed, the aluminum travels throughout the plant, including to the vacuoles within the cells of the flower petals. Within these vacuoles, the aluminum binds with a chemical called anthrocyanin, changing the reflection of light off the petals, making them appear blue!
In summary …
- More Acidic Soil (pH < 5.5) = More Blue
- More Basic Soil (pH > 5.5) = More Pink
Pretty nifty, huh? I bet you will never look at a hydrangea bloom the same way again … Have a lovely weekend!