Can grow to 6 feet in its second season, should be cut down in Spring, you may need to dig up and divide clumps as time goes by. How often you need to dig it up and divide depends on how fast the clumps become very large, but the fact it's mentioned as part of the maintenance tells me that it probably does spread a fair bit. Never grown it, so can't comment on how gorgeous or not it is, sorry.

Many thanks for writing, Bamboo.