Fungus is very common on Hydrangeas. This time of year, especially. Mostly it's a cosmetic problem. I'd just live with a small amount this time of year. I don't have a lot of experience with fungicides, but if you search google for "hydrangea, diseases, fungus," you can find plenty of suggestions for fungicide treatments. Basically you spray the plant every couple of weeks with some fungicide. Good luck. Hay.

Your flower heads are probably just naturally fading to their "fall" colors (they make wonderful dried flowers for indoor arrangements). I wouldn't recommend overhead watering as it will, as best, cause the flower heads to fill w/water and become very heavy and, at worst, help to provide favorable growing conditions for disease. With ample water, you can probably grow ES in full sun in Manchester but morning sun and afternoon shade during the hottest part of the day would be better. Keep your new shrub well watered right up until the ground freezes if nature doesn't provide.

To make it less traumatic for the shrubs, I would wait until temps moderate and Fall temps arrive. You can do it then or before leaf out in Spring. But choose the spot now that sunlight is very close to what it usually is at the start of summer. In the Spring, the sun will be lower, at a different angle.

Is it a heated garage? Did you water it while dormant? Sorry @luis_pr for the delay in replying. The garage is not heated (the coldest I observed inside the garage was -12 C/10 F while it was -22 C/-8 F outside) and the only water it got was from 'clumps' of snow that I would put on it every once and awhile through the winter. So here it was on May 17: And today, about 6 weeks later: I can tell you that it looks lots larger than it actually is, but clearly it is producing flowers (on strictly new wood).