I have never tried to grow it from seed , but in the gardens I have cared for, once established almost impossible to get rid of.
I would guess there is someone in your area willing to share a root or two
If not in the spring I can find some and send, I see it growing wild in some of the places I walk
I have the limelight one in my garden , basically the same but with a variegated leaf
I have never seen a seedling so maybe not propagated by seed