We are advocates for green roof solutions, but we are also tempered with a practical side! To make sure that we help our clients to choose maintainable solutions, we have been testing green roof systems on our roof terrace. We are at the end of the first season of testing in the most harsh conditions; no water, full sun and exposure, no frost protection.
The four pallates are low profile solutions with no more than 3″ - 4″ of planting medium. They were placed on the roof in spring 2009. We found the sunniest part of the roof terrace, including reflected heat from the adjacent walls. Other than placing them, we have not watered, fertilized or cared for them at all. All four have made it through an unusually hot Seattle summer and a reasonably cold winter with freezing temperatures and snow. This picture was taken this morning.
We have not taken measurements of percentage of cover, or rooting samples at this point. We are in the process of evaluating which Sedums performed best, and will continue to watch them and share our gained knowlege.

One Comment
I love reading posts like this, glad you guys are trying out green roof systems on your own. As an owner of a living architecture company (called verticiel Inc.) which specializes in green roofs, one thing I wanted to mention is that mosses are a great alternative for a roof where one anticipates a great deal of stress. But if one truly wants to use sedums, some sedums obviously perform better than others.