I received a few more plants on Friday and added them to the roof garden, in the hope of filling things in a little. I put in a couple of gooseneck loosestrife:
Summersweet (Clethra alnifolia) "Sixteen Candles":
Siberian iris "Snow Queen":
More campanulas, this time Campanula glomerata alba:
and the groundcover Mazus reptans alba, currently looking very wilted in the red brick building's garden:
I also ordered three cold-hardy camellias, but they haven't shipped yet. Curious to see whether they'll be okay up there.