White hydrangea's can either be the result of genetics or
neutral pH. You're right in that the former won't change
colour no matter how acid or alkaline the soil. However,
Sabaa said they were bought as coloured hydrangeas (I assume
they were flowering when they were bought) so it should
simply be a matter of changing the pH, especially since both
the red and the blue flowered plant now have identical
colours.
Andrew

alwynne mackie wrote:

You can change reds and pinks to blues and vice versa, but if the plant is
white or cream, no amount of lime or acid will change its colour.
Sorry to be a wet blanket!
Alwynne

"Sabaa Mundia" wrote in message
...
hi there,
i live in ny,(zone 7),i bought a red hydrangea plant 2 years ago from
home
depot. last it did not make any flowers, this year it has nice bug buds
out
of which some have bloomed but into a vey pale cream colour, i wanted a
nice
bright red.
i had also bought a blue hydrangea last year but this year it also has
cream
blooms,(the flower has not yet opened just one a few blooms here and
there).
i wanted to know is there any thig that i can do to improve the color. is
there any special fertilizer that i should put(i put miracle grow).
thanks,
sabaa