acid/base indicator plants

Frank Percival perciva at WESTMONT.EDU
Tue Nov 10 21:49:10 EST 1998

>Can someone please refresh my memory about this? I have two questions?
>1) Is it hydrangeas that produce red or blue flowers according to soil

It is hydrangeas, although the basis for the color is a little more
involved than soil pH.  The blue color results from a complex of aluminum
ions with (I think) anthocyanins, although I'm not sure that I am
remembering the pigment correctly.  Fertilizing with aluminum sulfate is
supposed to help keep the flowers blue.  Hope that helps.


Frank Percival              |
Biology Department          |    phone:    (805)565-6119
Westmont College            |    fax:      (805)565-7035
955 La Paz Rd.              |    email:    perciva at
Santa Barbara, CA  93108    |

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