Re: Moso bamboo from seed
From what I've seen with Moso it'll take a few years to be "hardy" in a zone 6. It will topkill most years, but is one of the very few bamboo species to be able to size up after being topkilled. This analysis is based on the well documented bamboo gardens of Brad Salmon in zone 6b Indiana. If you want to keep it alive use the 'tarp' method, just cover it with frost cloth in late fall (stake the plant to the ground and cover it), and uncover it in spring. It will stay green and healthy.
Bamboo is yet another of those plants that is listed as WAY hardier than it is. You see things like -20F for Phyllostachys aureosulcata, and then you see a brown plant after a winter low of -2F. Madness.