Alan, keep me posted on your Marigolds, when I divided mine, it died.
Course the divides I sold from it thrived. Not sure what I did to mine, but
I know the new one is going to have to be very big before I try dividing
again, and then I'll keep half, and hold the other half, till I know
they've both survived.

I can tell you one thing regarding MM, they will survive 0.3% over the
winter. This is the first winter I've brought the salt up so high, I did it
after lilies and the other plants had gone pretty much dormant, then I
reduced it just before things started to perk up. Only plant that seems to
have reacted poorly is the variegated water celery, but I see I have some
small starts on it, so HOPEFULLY, it will come back. I know some people
grow this like a weed, at least the green ones, but I divided this
variegated version two years ago and it hasn't been the same since.
~ jan (Do you know where your water quality is?)

Well, after a few days with no response from the group, I figured nobody out
there had experience with marsh marigold plants. I took a chance and divided
them as I would a hosta and it worked out well. So...

If anyone is looking to divide a marsh marigold, simply take it out of the
pot, pull or cut it apart at the roots and plop it in another pot (or bog)
as I have done.
Hope this helps other marsh marigold fans.
Alan