For nonwoody plants, in time the stems will rot and fall off. It is an aesthetic more than anything, as the old stems will look unsightly with new growth the grass will have green and dead foliage both for a period we say that the dead foliage gets in the way of the fresh green growth and it needs to be cut down "to make way for" new spring growth, but that is a visual thing more than anything. Yes, disease in old growth is an issue for some plants but that is not the norm. Pruning woody plants removes the old growth and encourages vigorus regrowth, but that is a complex topic. It depends on the context. Pruning can promote growth or keep plants short depending on the plant and how you do it,

I've grown globemaster and purple sensation. I did not cut the heads down last year (my first year for both) becuase I, too, like the structure. However, none of my 3 globemasters came back this year (bummer at $7 a pop) and I definitely lost some of the purple sensation. I'm thinking it may be because I allowed them to go to seed rather than save their energy for blooming the next year. Just my thoughts and experience...

It would take at least that long to grow back.

Thanks, I will keep it in the turface until I see more root growth. At this time though it is only a twig, there are no leaves yet. they all fell off when I put the cutting in the turface. I also keep it in a large plastic container with the lid closed. Makes it kinda like a little green house. I open it up every day or so for some fresh air. when I removed the cutting and saw the new roots I also saw some white growth, im guessing mold? I wiped this off and put it back into the turface and it seems to be fine.I think I may have forgot to let it breath once or twice and it got too moist! Thank you again for the great advice. I am hoping now that the roots are forming the roots will grow faster.