Possibly 'Nikko Blue', which is often a similar shade of blue and is known to be vigorous. But there are a lot of mop-head cultivars. Other than this example perhaps large 'Mariesii Perfecta' I've seen were the biggest. There seem to be a lot of it around and it tends to grow into a tub of a shrub.

One garden plant encyclopedia gives 2 m by 2.5 m as a typical size for Hydrangea macrophylla.

My Nikko Blues have always been dark or bright blue. I've seen a few around here like this one, mostly washed out in color....

If you consider this one of the "blah" hydrangeas, would you please show me some examples of the most exciting?

Looks like it's in a fair amount of sun, which has a tendency to wash out the coloring. And most of the blooms have already faded so that increases the "blah" appearance. I bet it looked pretty good earlier in the season when the flowers were fresh.

I have a client that has a couple of Endless Summer Originals that are almost that large.

They take full sun here quite well, that same washed out blue, as I think of it, was not much brighter at peak. Others with deeper colors don't wash our from the sun...just about everything takes full sun here...I've driven past that hydrangea everyday for about 2 1/2 years, doesn't really ever look 'good' or striking..just not really blue and not white.

But is that the plant, or the soil, or the lighting? That is, if it were not being viewed in bright western daytime light, might the blues appear more saturated?

I don't think so ...There are more in this color around town and they all appear the same...we don't really have "bright western daylight" right here on the coast where that might be a factor inland. I don't think it has anything to do with soil conditions such as pinks vs. blue with acidity or alkalinity...just the color of that particular hydrangea.

It appears that hydrangea is getting an assist from a downspout up in the left hand corner that enables it to look as good as it does in full sun. Most hydrangeas are past their prime now.

'Weiderspink' is my favorite ...for now.

This one is from a supermarket florist shop. No name, of course.

Another supermarket special.

Mike

A bunch of mine have no names since they were given to me by a friend who closed her nursery and I was the happy recipient of a lot of leftover, NOID, plants..surprises are fun. The clumps of carex she has given me have surprises also...juncus, dierama, schizostylis, gladious papilio...evey day is a new adventure...LOL...

I have a friend who has mentioned that all of his hydrangeas have come from a cemetery he goes to visit where he has family buried. After all those 'take a plant to the grave' kinds of holidays, when the grounds crew tidies up, there are sad looking pots of hydrangeas in the clean-up area....something to think about.....hmm?

Not that there aren't a lot of different kinds but Mike's first picture resembles 'Mariesii Perfecta'. Also when I Bing "weiderspink" his references to the plant shown are pretty much the extent of relevant hits that come up.