Oh the plant seeds itself, whenever it does, in the fall I presume and just on the surface
I can try to collect some next year--it requires a timing thing that I cannot promise to master given my work schedule though.
...but, I will have seedlings this spring
Leslieray, I think you should be tempted
I don't know, does it look bigger than it is? perspective can be funny thing--
It is supposed to get 36-48 inches (90-120 cm) tall--I'd say mine tops out around 50inches.
so sorry to recycle this picture, again--but to see it whole-- it is there behind the agastaches, to the left of the amaranth, not blooming yet--it is more than one plant in the clump. I planted two, together, and then it made more.

you can see one of the seedlings I missed --far left behind the origanum (purple thing) in front of the orange rock, more typical of an individual young plant.
My soil is lousy--this is a gravel, sand, and clay bed that got compost once a few years ago