Problems and solutions are always good discussion fodder! You could start a new thread or post on the "yardening" thread here.
My lantana didn't keep blooming through the winter, but it's still around. I didn't water it much inside, and it didn't grow, but it survived as this little green plant.
I wouldn't worry about the concrete shelf, just plant in front of it. A happy 'Arp' can get 2-3' wide. It'll love the heat sink of the wall, and I don't think any alkaline stuff leaching from the concrete will bother it a bit.
I've never had much luck with rosemary cuttings, but I haven't tried "hard" either. I have heard that a bubbler setup works. A friend's brother did a bunch of different cuttings with a sort of mist hydroponic thing where the tops stayed dry and the stripped bottom of the cuttings stayed misted.
Here's the "yardening" thread:
The thread "Yardening in the Mid-Atlantic" in
Mid Atlantic Gardening forum
