Here's what I do with mine - I trim each stem back to the point where you have only 2 or 3 sets of buds on each stem. also remove all the smaller thin stems that make exist. Once you get growth coming from the buds, keep the strongest and most upright growing stems - prune off the others. And remember the blooms normally appear on the end of the stems. Paniculata don't like dry conditions so if you experience that, water once a week - I like using one of those Ross root feeders and water deep. Fertilizer - if your soil is decent, none. If your soil is poor I'd suggest a balanced formula like 10-10-10 or any good garden fertilizer. And top dress with compost every year.

Looks like sagging from too much water/rain (especially looking at the leaves). Trim the long stems to ~36" in the offseason they will become thicker year after year, to support upper foliage/blooms. Consider "mounding" the bed a little and raising the root ball a few inches if too much water is a potential issue. Here is close cousin Great Star. It's approaching 7' and a little sprawly, blooms bend over the stems after heavy rain. I'm going to trim to about 40" max (the fence is close to 48"). Should make for a fuller branch structure next time around.

Well, I enjoy pruning and directing shape. I try and get to newly installed shrubs during their second or third year to sort of make sure they are growing evenly and in good proportion- no wacko branches growing wild or ruining the form I have in mind. I like to do this while they are still small enough to get into and around easily. After their basic shape is established then going forward I have to do very little. I look at them each spring before they leaf out because it's easier to see their structure then and I clear anything that does not fit into my idea of how I want them to look from my primary viewing angle. Most of my paniuclatas have ground cover or smaller shrubs in front of or even underneath them- these I clear out some of the lower/smaller branches. I have a big yard but even then I always seem to need more space with dappled sun for hostas etc. and this gives me tons more space than if I let the hydrangeas take up all the space underneath. Here's a huge Quickfire (fence is six feet) that shows how I lift up the bottom to allow space for plants underneath and around it. There are some young hostas and other things under there.

Thank you everyone for taking the time and care to advise! Though I must say now I'm still a little confused about what to do. :-D I have read online to move plants early enough so that the root system re-establishes itself before winter dormancy, and then other articles about hydrangeas specifically that state one shouldn't move them UNTIL dormancy. That's why I thought I'd ask here. But it seems like there are folks having success either way, so maybe they are hardier (and/or heartier) than I imagine them to be, at least with the right amount of TLC. One other option I have considered is doing something similar to what hyed has done and prune and reshape the hydrangeas under the window, fronting them with some miniature boxwood type shrubs. But I would still have to end up moving two of them (albeit just steps away rather than several yards) because they aren't lined up and are growing out into our very small yard. I also spend almost all of my available time in the back yard gardening and playing with my veggies and flower beds, and really want to keep it that way. So I question how "good" I will be at keeping these shrubs a manageable size if they remain in the front. I really do think they would be great as a screen in the back yard along the fence line between my house and the neighbor's house, so my inclination is to move them and let them do their 10 foot spread with abandon there. One additional question once I've settled on the question of "when or whether" I should move them, is what kind of fertilizer do y'all recommend to help them along? Thanks a million!