Can you post some pictures of your seed heuchera? Sounds interesting. Caroline, I planted seeds a few years ago. Just collected seed from many of my plants. They were just bee pollinated and I didn't keep track of the parent. Hard to get all the chaff out of the seeds so I just sprinkled all in a seed flat. Then covered with a plastic cover to keep moisture in. Really didn't think they would sprout.
Here is what grew
This is after spending a few hours pulling seedlings,potting to four inch and growing on all summer. I had so many!!!
I planted these on a hillside.
They sprouted in about a week to ten days. Seemed very easy, good luck Caroline and keep use posted on what happens.
Edited because I posted pictures before, sorry. Here's the link:
The thread "My Seed Heuchera"
in Heucheras forum