Endless Summer is not my favorite hydrangea, but that doesn't answer your question. :-)

If someone here can't tell you, I'm sure you can get answers on the Hydrangea Forum. But my first thought was to consider a paniculata (Limelight or Pinky Winky, for instance) instead of a mophead. Paniculatas aren't water hogs like the macrophyllas. When we had a long stretch of super-hot, dry weather this summer, the mopheads got droopy in a hurry (in half sun), but the paniculatas (one of them in full sun) never showed a sign of wilting.

Pricey? Is she selling you an especially large shrub? I paid $7 for each of my Limelights last year. They were small, but they're getting big in a hurry. I think my Endless Summer cost $15. It blooms very poorly for me, but it dies to the ground every winter. It may do better for you.

Sadie Ray is said to be a very hardy mophead, and I love mine. But boy, did it wilt in the hot sun.......

What about Annabelle? Not strictly a mophead, but close enough, maybe? She's on my shopping list, but I don't know anything about sun tolerance.

If you've observed established mopheads in your neighborhood, then it's fine. take your cues from your neighbors and your local garden centre. Do they guarantee the plants they sell? My garden centre does so if the plant dies within a year, they will give me credit or replace the plant.

also, don't plant in the height of summer. Wait till fall to plant

I have Annabelle, planted on the east side of a building so she gets all but the very hottest west sun. I love her! I do very little supplementary watering, but if the leaves wilt, I do.

I also have Limelight and positively love this shrub. I agree much safer than the true mopheads and mine has grown pretty fast. Here is a picture of it in the third year:

I also have Endless Summer planted on the east side of the house. I don't think she could stand full sun unless you had a drip line for water right at her feet. She was slow to ever bloom much but this year at about 4.5 feet tall put on a nice show. They don't last nearly as long as Limelight which looks good from June until frost.

Actually, the spot in question is between pinkie winkie and limelight! lol I adore limelight, its my favorite shrub. The nusrsery has endless summer for 35, which for me is a little much but its a good size. I think tho, i might wait for that vanilla strawberry hydrangea to come out. or ill keep looking because the spot is right under a window and i didnt want the shrub to cover up the window. I appreciate your thoughts!

I wouldn't give an ES full sun. Sun until noon or 1 would be perfect though, but you'd still have to water everyday.

How much sun does your neighbor's plant get?

I have two and I'm not pleased with either. In early summer they put on blooms, then just sit there and do nothing until winter.

I have to admit though, I didn't feed them much this summer.

They shouldn't be fed after July, so maybe I need to get out there!