My Hakonechloa macra aureola (a variegated Hakone grass) has a tendency to revert to a solid green. Whenever the solid green appears, I dig it up & plant it elsewhere. The solid green still has the graceful motion of its parent plant but is without the 'bright light' effect in the garden. Here is a photo of 2 that I had just transplanted. The Solid green Hakone is (of course) hardier that the variegated one & grows faster too.
