Looks like H. macrophylla 'Glowing Embers' to me. 'Pia' is also similar but the leaves on it aren't as wide. 'Merritt's Supreme' has wide leaves like that but the stems grow longer in between leaf sets.

It has probably grown at least two seasons in its extremely shaded spot before I transplanted and therefore stunted, so I am hoping the branches will grow out through this season. This little guy was pretty bare after the cold winter we had this year, but has rebounded quite nicely. I am just hoping he can stretch his legs and grow out a bit.

Do you suppose I could put another one next to it? As you can see, there's a bare area that used to have a tall grass growing behind it, and I'd like to add some more hydrangea, maybe some that would go strong blue but end up more purpley with the alkaline soil.

GE doesn't grow that large (~3'). In that scenario, you could add one every three feet or so to fill a space. H. macrophyllas can grow up to 6' around, so you'd have to be careful which ones you choose.

You can grow absolutely anything in zone 9a, though, so sky's the limit.

Fantastic. Thank you!