The Master Gardeners of Northern Virginia, Wisconsin Extension, and a few other references say that Chelone can be divided in spring, but they do not specify exactly when (before dormancy is broken, for example, or later). We don't know if it's too late right now, but you can try it if you want, making sure the plant is monitored carefully for watering needs afterwards, depending on weather. Otherwise, it might be safer to wait until next March or April; this is not something we have studied locally.

Miri