@HorseloverFat
Your bamboo seedlings could be any of several hundred species. Those seedlings are so young they do not have any identification traits. My first guess would be genus Phyllostachys, or possibly Pleioblastus. Both genera are temperate climate bamboo, mostly from China. I am certain your seed is NOT Fargesia. With Phyllostachys and Pleioblastus in mind, this bamboo will not be winter hardy in your climate. Most Phyllostachys & Pleioblastus do best in zone 7 winters. There are a few specific species that are winter hardy in zone 6. I have a few species that are hardy, in the ground at my zone 5b home, but none of them are likely to be available from seed. So plan on your seedlings being winter hardy to only zone 7. At the small seedling size, you might want to avoid letting the pot and soil freeze at all for the first few winters. A light frost is okay, but don't let the roots freeze solid.
I wrote a lot about bamboo over the years. Use the site search function to find posts about bamboo, authored by me. A couple of note are
I've acquired a bamboo plant. It was given to me. The thing is, I don't know what sort of bamboo it is and if it is suitable for indoor growing. Does anyone know anything about bamboo? Here's what it looks like.
www.bonsainut.com
A discussion of
@AlainK 's Pleioblastus (the name I consistently misspelled through the post)
I was given this plant that looks like a small bamboo. It's been in this little pot since the spring and is less than 10 cm tall (4 inches). I also don't know if this plant is hardy, or not. If it's not, it could be a Pogonatherum. I've often seen it as an accent plant but can't find the name...
www.bonsainut.com
a post about gregarious flowering of bamboo
A post about grooming an in-ground grove of bamboo
another brief mention of maintenance of a bamboo grove