In the colder zones of 7 'Ogon' will go dormant/semi dormant.
My son's neighbor in Annandale, VA has had it growing outside for a number of years. It comes back every spring, and has made a most beautiful large colony underneath a Japanese Maple.
I took this photo the end of November while I was visiting. The colony covered the entire space under the maple.
It's a good idea to cover your base though.
