It is always best, if possible, to buy hydrangea while they are in bloom. That's the only way to know for sure what you are getting. For some reason, the tags on hydrangeas in garden centers frequently get misplaced or lost, so you can never be sure what you got until the blamed thing blooms.

I agree with you--if it bloom white, there is no way it will ever turn blue, regardless of what you do to it. It has to do with how alkaline or not the soil is--the (correct) bush will turn blue or pink or a kinda half-and-half (gives a kind of lavenderish pinkish bloom), but it will never yield a white.

I don't know which blue one you were hoping to get, but since you are in Zone 5, beware that common macrophylla hydrangeas like Nikko Blue probably won't bloom well in your zone--the buds get frozen off during the winter. The macs in general are not good in Zone 5.

Kate (whose white paniculata hydrangea which was supposed to turn pink DID NOT! GRRRRR!)

OMG !!!! Thank you Kate, for such great info! Yes...GRRRR! I wish the fairies that attach those plant tags (not just on hydrangeas either) would pay a tad more attention. Well, I guess I am stuck with white ones. However, they were quite large and attractive enough so I did enjoy them as did my husband. Here's praying the other ones that did not bloom this year, will next year. Or else I will, once again, be seen transplanting around the yard, which I dare say I am becoming known to do.

Hi again kgmax! Tags are for marketing purposes, and are dubious at best. After working in nurseries, I have decided that "full sun" is the default option they use for most plant tags, including some that grow well in shade!

The colour of your blooms is controlled by 1. the type of hydrangea, and 2. your soil. If you are planting in clay, chances are you have alkaline soil and even a blue hydrangea will turn pink at best (or washed out gunmetal gray at worst)!

If you really want blue, I suggest buying from a reputable grower and planting in a very large pot. This way you can easily control the pH of the soil. You may need to cover the plant and pot with mulch in winter to prevent damage to the buds.

It was said "If you are planting in clay, chances are you have alkaline soil "

Not necessarily so. My clay soil has a pH 5.8

To determine the prevailing pH in your region, call your county's Extension Service office.

Locate your county's office it this USDA Map
http://www.csrees.usda.gov/Extension/

Here is a link that might be useful: locate your county's Extension Service office

jean001a, The original poster and I are both in Ontario. We do not have extension offices in Canada. Most areas with clay soil are alkaline in Ontario. I do have a daughter in Oregon, and it is not surprising yours is acidic given your location.

The clay soils typical of southern Ontario tend to be luvisols that are calcareous.

Regardless, a white hydrangea is never going to be blue.

If you want a pink one, try Endless Summer. It flowers on new stems so winter kill is not as devastating. Unless you live on the Canadian Shield or endlessly amend the soil with acidifying ingredients, it will never turn blue.