Aluminum: The Missing Piece Most People Overlook
Acidic Soil Isn’t Enough by Itself
You can lower pH and still not get blue blooms if the plant can’t access aluminum availability in soil. This is the part most garden center labels leave out.
How Aluminum Works
When soil is acidic, aluminum becomes more available in the root zone. The plant takes it up, and that changes the pigment in the flowers toward blue.
Locked-Up Aluminum Is a Real Thing
Some gardens already contain aluminum, but it’s tied up because the soil pH is too high. That’s why people use soil acidifier for hydrangeas and still wonder why the flowers stay pink.
Too Much Can Hurt
I’ve also seen gardeners go wild with aluminum sulfate for hydrangeas and stress the roots. More is not always better, and hydrangeas can get cranky fast.
So now we know the chemistry, but the next question is huge: does your hydrangea even have the ability to turn blue? Hit next below.
