Vicki, variegated Hydrangea macrophylla Light-O-Day will be about as tall as wide, somewhere in the neighborhood of 3-5' - although it could experience winter dieback in a Z6. The variegated leaves would make it even less likely to perform well in sun, and the type in general is better in only morning sun, supplemental water. It blooms on the previous years growth - flower buds may not be cold hardy in your zone.

I think what you are looking for would be better found in the hydrangea paniculata forms, or pee-gee hydrangea. They are a available in a variety of heights and lend themselves to shaping to tree form, bloom on current years growth so would flower for you reliably.

Hello,
If you're looking for a hydrangea tree that can take a sunny location, the Quickfire, Limelight or the Pink Diamond would be great options. All of them come in tree form so you don't have to do anything on that front. Cottage Farms sells a Limelight and a Quickfire that you can purchase from QVC. I ordered two Quickfires and I'm waiting for them to arrive to be planted. I'm in CT so they've just begun shipping because of my zone.

I already have a Pink Diamond hydrangea tree that I've had in my front yard for about six years. It came in a tree form and it's beautiful when it blooms. The only issue I have about the Pink Diamond is that it's still only about 5' tall. The mature height for it is supposed to be 8'-10'. I guess the time frame is questionable because it's very healthy so I don't know if it's just a slow grower or what.

With the different material I've read, I've learned a few things that I will try to apply this spring/summer. Hopefully, that will make a difference in the size. I hope this helps!

CeeView

Macrophyllas do not make for good tree hydrangeas because they do not grow tall enough but paniculatas tend to be the ones to use for this endeavour as some will get as tall as small trees. Post pictures of your tree when you get a chance!

Tree hydrangea can take 10-20 years to reach decent heights, just as most other trees do. A great amount of energy is required to grow main trunks long and thick.

I would like to know how they train knockout roses into trees. They are neat but expensive!

They graft KnockOut roses onto a tall rose cane (like from a large growing shrub rose or grandiflora). And there IS a limit on how tall a tree-form hydrangea will get. Since these are trained and not grafted plants, you can only expect a mature height at the upper edge of the same plant grown as a shrub. Unfortunately, there is not some magic potion that allows the tree forms to get sisgnificantly taller :-)