Hydrangea: Who Knew?

I've often wondered about my hydrangea bushes.  They can't seem to decide what color they'd like to be when they grow up.  See the lavender and pink flowers?


Well, that's not accurate. Correction: there are purple and pink sepals on the same cluster.  Sepals are modified leaves. It turns out that hydrangea flowers aren't flowers at all.  

Who knew?

I've always thought that hydrangea color is related to the pH levels in the soil.  But that doesn't entirely explain how there can be multiple colors in one cluster.  I decided to dig (HA!) deeper.

The reason for the different colorations is a biochemical reaction involving aluminum ions bonding with the various ions in acidic or basic soils, such as hydroxide or calcium hydroxide. The resultant ion combinations interact with the pigment in the sepals, with different results from basic and acidic combinations.

How much pigment is changed, and with what ions, is the factor that influences color since, it's been discovered, the pH level of each individual sepal is the same, regardless of the color.  pH isn't what changes the color.  Aluminum ion levels do the trick.

Who knew?

If you'd like to learn more, here's an article from American Scientist that explains it all.

Comments

Norma Schlager said…
Beautiful and interesting. Now if I just knew why my hydrangea has NO flowers this year.