Can get as wide as 3-4' after about 3 years. Will really increase in size indefinitely but the center will die out if not divided every 5-6 years. And yes, I would go ahead and divide now. It just gets harder to do the longer you wait :-)

Great thanks... Ive never divided them before... should I use something serrated, even a saw? thanks!

Yes, you will probably need a saw :-) Dividing an ornamental grass rootball is kinda like sawing through a tree. It is very dense and heavy!

I use a hatchet.

A hatchet, eh? Tough buggers...