Chances are these new hydrangeas will perform like the hydrangeas you already have. That is surviving, but never blooming unless you winter protect them. Living in Zone 4 I have never bothered to try figuring it is a lost cause. However I do have several Endless Summer hydrangeas that bloom nicely despite freezing to the ground each year.

"... no mention of what zone they can be grown in, or any mention of the botanical name."

For future reference, this should raise a red flag. A gardening site should provide both botanical names and hardiness ratings. Even then, I would check several references for hardiness since it is not an absolute or some websites have a tendency to be "generous" with the ratings on the cold end of the spectrum. Or websites will just say "hardy", but that seems to me to mean it will survive in zone 6. Or the plant may be hardy, like the hydrangeas you have, but the websites don't mention that it will never bloom. You can get good info on a forum like this before you buy or check with a local, reputable garden center. They will either not sell the plant or sell it with the warning that it needs winter protection.

Thanx for the advice ginkonut! After I posted that message I found another thread, which didn't speak kindly of that website. I guess I am going to wait and see what happens with the hydrangeas and ALL the other plants I ordered form them.

So you are growing endless summer with no winter protection?? That sounds like it would be worth a try!!! Do you do anything "special" to them at all?

I just put some leaves over the crown of the plant in November or so. Other than that, they are on their own. They have only gone through 2 winters. This past winter was quite mild with decent snow and they still froze to the ground. I think the lowest it got was about -12F.