I am well aware of how aggressive this clematis is. I made the mistake of listening to a suggestion that I use it as groundcover in a certain situation. I changed my mind about five minutes later, but have been digging out (with a spade, not a trowel) the seedlings ever since. I think this obelisk will be a one-season thing. I am wary of creating too many fussy plantings that need surgical precision to control lest they become landmines. What if I wanted to go away some September? Or the unsuspecting next owner didn't know how important it was to remove every blossom before it went to seed?

It is never too late to prune a clematis :-) Yes, it could delay or alter bloom time but in a mild climate with a long growing season, it is not going to have much of an impact. When I worked for a wholesale grower of clems, the vines used to get cut back routinely every month or so just to keep the pots/vines from becoming tangled up with each other. All this did was to encourage more basal stem growth, generally considered a good thing :-) Never affected the flowering to any significance.

In my insanely stuffed garden, I am also fighting continual couch grass invasions (another hateful rhizomatous thug)...where I have to make temporary tiebacks using bamboo or hazel poles, lashed about with string, in order to hold back the roses (because they are the worst culprits. Fairly sure you could do something similar with the perovskia - tie it in a bundle and guy rope the whole thing to the side. I would also be reluctant to remove any later sources of bee sustenance as this is their main storage season to get them through winter. I hang onto the unsightly climbing ivy and goat willows as they top and tail the bee season, providing essential sources of nectar and pollen...especially the ivy which is the very last flower source before winter shutdown.

A fellow experimenter, Ken. :-). I agree, the things you learn the best are usually from your experiences and finding it out for yourself with a test. I'm not doing as much experimenting as I used to. I think my garden is more established than it was. And I got busier. I have clay/loam, and my sedums are in a mixed bed. I have only one full sun bed and I throw everything in there and a lot of plants that need more watering. I can't always hand water, so I put the sprinkler on it and they all get the same amount of watering. But, it's good to know that is what you are aiming for, less water and no fertilizing. They don't get fertilized per se, but the bed gets a deep leaf mulch every fall. I have more than enough Sedum Autumn Joy, but I do have a new dark leaved sedum that I love, called 'Black Pearl'. Finally a dark leaved that is really dark. It's not a fast grower, so I'd rather not wait to divide it. I think of taking cuttings, but I always feel that rooting sedum cuttings is very iffy for me for some reason. I feel uncertain about the directions to cut them and then leave them alone for a couple of days, lying on the surface of the soil. I know, of all things that are supposed to be so easy to root, I shouldn't have trouble with that. Here's the Sedum 'Black Pearl' to the right of 'Savannah' Rose, last season. And two very large Autumn Joy behind.