On Mon, 21 Jun 2004 12:21:42 GMT, "Jutta Haas"
wrote:

I apologize if this has been asked before, but I never saw the topic. Are
there any household potions I can add to my potted hydrangea to make the
blossoms blue? Or do I have to buy some commercial product, and if so what
is it? Thanks

I picked this up here some time ago and never tried for (pH greater
than 7.0) red, but epsom salts (magnesium) gives a nice purple color.

Use the following to determine final bloom color (determination of
bloom color is set approx. late Aug-early Sept.):

pH 7.0 = red
6.5 - 7.0 = white
5.5 - 6.5 = pink
4.5 - 5.5 = blue
4.5 = purple

pH control for plants: to raise pH, use hydrated powdered
lime at a rate of 1.1#/100sq.ft. to raise pH 1pt. for heavy soil.
To lower pH, use ironite or iron sulphate at a rate of 2.5#/100sq.ft.
to lower pH 1 point.
For 10sq.ft. (size of large hydrangea) area use 1/4 lb. of ironite,
which is 1/2 cup.

VG information
To acidify the soil, use aluminum sulfate, which provides aluminum as
well as lowers pH, mixed 1 pound to 7 gallons of water. Soak the
ground with it after the plant starts growing in spring and repeat
twice at two-week intervals as necessary to lower the pH 1/2 point. To
raise the pH 1/2 point, spread ground limestone in spring or fall at a
rate of 5 pounds per 100 square feet.

Regards,

Hal