A good thick (2-3") mulch of compost is all they need, especially their first season in the ground. If you want to encourage bluer flowers, work some cottonseed meal into the mulch. Or use worm castings or coffee grounds, if ya got 'em :-) Fertilizing doesn't have much of an effect on the length of bloom, unless one errs too far in a single direction, but that typically results in a shortened or nonexistant bloom, not longer. Compost will result in overall good health and is 100% natural. And will help retain moisture in the soil.

I agree with everything said. No fert. let them establish, sounds like too much shade, but they are fine, winding down especially for new plantings. However, all you have is 5b, but I will highly recommend winter protecting them. I know they are marketed as winter hardy, and they'll make it. But, if you want blooms next year, especially with the amount of shade, I would wrap them up for the winter after freezing temps. I use burlap stuffed with straw. You can also use leaves. Huge difference after experimenting with uncovered vs. covered here in Northeast Ohio. Just one example; http://forums.gardenweb.com/forums/load/hydra/msg0821023324059.html?22

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.

I typically leave a minimum of 1-2 feet between my house and plants so I can get in easily for maintenance. The width given is often a width at 10 years, so shrubs may get a bit larger than that, so keep that in mind when choosing how close to plant. So for me, planting a 5' wide shrub 2.5' from the house would be too close since the shrub will be growing against the house eventually which will be an issue, particularly if this part of the house has a siding that isn't masonry. I would be planting it more like 3.5' from the house. One thing I am confused about - there is a H. macrophylla Firelight and a H. paniculata Fire Light. Which do you have? The tag should say, and this will change the advice given. Are you planting them in a clump (2 front and 2 back) or in a line of 4? Can you provide a photo of the spot? Where are you generally? How large Endless Summer will get depends on growing conditions, particularly whether it is killed back to the ground annually. Here's how to add that to your user profile so it shows up in all your Garden Web posts: Go to Your Houzz in upper right of every page, click Edit Profile, and on the left side click advanced settings. Well down the advanced settings page is a blank labeled Climate Zone for Garden Forums along with a link to find your zone. If you add info on your state or the nearest large city you will get even better information since zone only relates to average coldest winter temperatures. Then return to the top of the page and click Done Editing.