Native sedums for green roofs - Sedum ternatum

For years I've heard about Sedum ternatum; one of the few native (to North America) sedum species plants which seems to do well with little sun (or even shade) and moisture. In a green roof we completed last June we put some (and a few sedum pachyclados) underneath a couple of river birch. In the height of the summer the plants get perhaps 3 hours of full-sun. I wasn't sure if they would flourish, in the medium after four months in place they had barely grown, but they have really taken off this spring!

Sedum ternatum is the lighter colored one, the darker one is the sedum pachyclados.