it is frost hardy and yes you can let it freeze solid over winter. I got mine from a fellow down in Calgary a few years back when he discovered it is unstoppable.

Calgary Alberta?

If so that's funny as that's where I am!

Thanks, I guess I'll put it outside. It shouldn't frost but the weather is unpredictable here....

Yep that Calgary I am up in Edmonton. the fellow that I got them from said he hadnt expected them to winter and brought up a big clump for me. If you get up this way I would be more than happy to share some sedges and water avens that are running wild also yellow flag iris and a purple iris, think it is called Gerald Darby

I would really like to have some! But I don't have any space left around my pond and half of my pond is in almost full shade and I doubt they would really thrive there... Thanks for the offer though and help! Maybe some time in the future, that is if I finally get fed up and knock out all the yellow loose strife... One day. One day.

Typha minima occurs in Siberia.