If you got the Bocking 14 sterile variety, it's not invasive, just never run it over with a rototiller.
It only spreads from root chunks. The invasive stuff spreads by seeds.
But, every time I've moved a Bocking, no matter how carefully I dug it up, it eventually popped up again in that spot. The xplanted plant never seemed to notice it was xplanted and just kept going. A root chunk the size of the end of your thumb is plenty big.
An easy way to propagate is, when it flowers, simply root sections of the flower stalk. I've had them root in the worm bins when not dried enough in the sun to make sure they were dead dead.
Wet