Hydrangea arborescens (like the Annabelles) and H. paniculata should do fine. They are both very cold hardy and bloom on the current season's growth.

Hydrangea macrophylla - like the Endless Summer - offer the colored flowers but are not very cold tolerant and will either dieback in cold winters without protection or suffer flower bud damage that prevents flowering. Even the so-called rebloomers (like ES) struggle after a cold winter and may or may not produce any flowering from new growth. Some of the newer intros may be more reliable in this regard but since winter cold is not an issue in my climate, I can't say which ones are better.

Some of the serratas or mountain hydrangeas are more cold tolerant than the macs and will bloom pretty reliably after a cold winter. They also offer colored flowers but as lacecaps, not mopheads. 'Blue Wave' is a popular selection.

And there have been reports here that oakleafs will produce flowers relatively reliably in colder zones. https://www.gardenweb.com/discussions/2810482/oakleaf-hydrangeas-and-late-freezes#n=12

I am in the 7a part of east Tennessee. 'Annabelle" also does very well for me. In regards to your question about oakleaf hydrangeas (H. quercifolia)..they should do well for you. I see them frequently planted here in the Knoxville area and they are usually very healthy looking plants with nice flowers and lovely fall foliage.

Annabelles have done very well for me in midTn--I've had them with both a western and northern exposure. Oakleaf do well too, where I had them the had morning sun and afternoon shade. Endless Summer has not done well. They had morning sun, afternoon shade and were cuddled up to the side of the house out of the winter wind, but no amount of water was enough for them in the heat of summer and they promptly wilted every afternoon. They no longer live here! I'm currently trying out Little Limes. They were planted last spring and came back well this year, so far so good.

I just wanted to come back to this post and say thank you so much for the help! last winter I moved all of my ES to a new spot and babied them (covered during frost), but recieved no blooms, so I am pulling them all. My annabelles do absolutely wonderful here, so i took all of your great advice and purchased a variety of paniculata and arborescens.

They are set to arrive this week and I’m so excited! I’ll update next spring with pix, but for now i wanted to say thank you for your help!

I live south of Nashville.

Lime and Little Lime do well for me, even as a novice.

I planted ”blue enchantress” from Monrovia last spring in mostly shade around the foundation.

5 of them in quart sized pots.

They all bloomed and have all survived winter with no additional protection.

Waiting to see how they do with a year in the ground.

spswash thank you so much for the great advice! hydrangeas are my favorite flower, but i havent had much luck here. I’m thrilled to here about the TN nursery b/c their advice will be so relevant for me. Thank you so much!! i will definitely reach out to them!

@jc_7a_MiddleTN For some reason I thought you were north of town...We might be neighbors!

I've pretty much given up on macs. I'm lucky if I get 2 blooms. Endless Summer doesn't live up to the hype. I only grow the white flowering ones that bloom on new growth. Oakleafs are way better than macs any way. The flowers last way longer and they turn pink. The leaves have nice fall colors. The only issue is they get big. Even the dwarf ones.

I have seen really impressive oakleafs in the area.

@subk3 im in rutherford county

Endless Summer is also called Endless Bummer in many zones. It is wonderful in the PNW but pretty iffy in the rest of the US.

Late summer bloom, color stays for weeks.

Color change from blue to pink/red

Final red color in late fall