Bunny tail grass
I have never grown this before, the seedlings are about 2 cms high, when do I transplant them?
I'd wait for them to grow a bit higher, say 6" or so then transplant them into the ground in clumps. They are brilliant because after that they self seed and come up every year and they're easy enough to pull up from places where they're not wanted as they're only shallow-rooted. Mine have been going for several years now and are always a joy to see.