My husband and I recently moved into a house that had been sitting empty for about two years. The house is U shaped around what you might call a solarium or greenhouse -- it has a glass domed roof, paved floor, etc. I'm thrilled with it, though the roof leaks and needs repair... but here's the question.

In the center of the room there's a patch about 10 or 12 feet by 5 or 6 feet that's filled with geraniums. They're about four feet tall at the tallest, have a lot of new growth, have been blooming non-stop since I first saw them in December, have a lot of "dead wood" underneath, but otherwise look healthy, thriving, and kinda amazing to me (considering the lack of care they've had for several years!). I didn't even know what plant they were when I first saw them, so that gives an idea of my background with them...

I found out a week or two after we moved in that there is actually a koi pond in the middle of the "patch" of flowers. The plants seem to be planted in dirt and have overgrown the bounds of the in-ground planter (or what I'm guessing is that!). I'd like to trim them back to the edge of the planter or behind, and to trim them so they don't completely cover the several foot deep hole that could be a pond. I'd like them to look good in the end & I'd like to use as much of it as possible to make new plants rather than throw them out. I knocked off a "branch" of it a week or so ago and having looked online briefly I took the little shoots and stuck them in potting soil; they seem to be doing OK, but I don't know how to tell if they're suddenly going to die on me or something.

I'd love advice as to when to cut these back, how to do it, if they'll ever grow from the bottom again or if I cut them back so the root structure is showing if it will always look bad, how not to kill a beautiful set of plants (I don't even know how many separate plants there are in there!), how much to water them once we get the roof fixed so it's not flooding the floor (which I'm guessing is how they've survived the past few years - and not only survived but apparently thrived), and whatever other advice you might have.

Thanks!!