I have blue flowers on one that is planted in the garden, because of the high aluminum content of the soil. One that is growing in a pot, using commercial potting mix and ground pine bark as the medium, has pink flowers.

Some gardeners that prefer link flowers, add dolomitic lime several times a year to elevate the pH of the soil, but that doesn't always work. If the aluminum content remains high, the plants may produce blooms with purple or lavender hues.

Below is a link to a website that discusses changing the color of Hydrangea blooms, plus a lot of other good information about growing them.

Here is a link that might be useful: Hydrangea color change

You weren't the only one surprised!

Mine started blooming approximately 4 weeks ago. Imagine my surprise when I saw the blue flowers on a "lady in red". I started searching at Google and found several people complaining of just the same. I read it either at the McCorkle site, or the Lady In Red site, and read that blue was common for the center flowers, and the outer flowers range based on pH. Regardless of whether the outer flowers are blue or pink, they will fade to red (supposedly). Some of mine are already all the way through blooming, but the outer large flowers are falling off.

Just want you to know that I've shared your surprise! You're not the only one! And there are many others of us out there from what I'm finding at Google.

Guess I will scratch that one off my list of wants. I have enough to do without having to modify soils for bloom colors.

Hydrangea macrophylla was always that way, vroomp.

It still looks pretty, just not red! Mine was quite a vivid color, more like "Lady in Electric Blue". It has faded to a sort of purplish color.

Has anyone's faded to red (without adding any lime)?

My H. mac "Blushing Bride" is also blushing a very light blue, rather than the pale pink shown in pics online. Its pretty too, as long as you like blue.

The oak-leafs don't seem to be sensitive to pH -- mine has big white flower heads that are turning a nice reddish color on the lower flowers.

mine are fading to red (the flowers) as they age. started blush pink, then went purple, then blue, and now turning a blood/brown/red color sort of.

but the beauty of this isn't necessarily just the pinkish red flowers. it's the fact that the stems and veins are dark red on deep green leaves, and the leaves turn deep burgundy in the fall, reminiscent of a loropetalum.

i am happy with mine =)