I am trying to grow them now, I have many seedlings but they aren't growing any new leaves. Its been three weeks and they haven't grown a bit. I hope they don't shrivel up. good luck.

I have some B. cylindrica plants on my property that thrive on the field lines of my septic tank. Seedlings come up all around them each year, and most of them live and grow to about 6' tall - I think it's the constantly wet soil that does it. There are also several plants in my garden that get watered during dry spells, along with my other garden plants. The one thing even mature false nettle plants can't tolerate is dry soil, young plants tolerate it even less - they grow naturally in ditches and other very wet spots. If you've kept your seedlings constantly moist and they still died, then I don't get it. Maybe the grow lights dry out the soil? Most potting soil is pretty light weight, drying out pretty easily.
If all else fails, you can always order a few plants, then keep them moist so that the seedlings that come up around them can thrive.
Sherry

They love moist soil. Sometimes the seed will take up to three months to germinate. They grow super slow as fresh seedlings but once they get to an inch or two, they begin to grow faster. It's the easiest plant to root. Don't cover the seeds with more than a breath of soil. They are so small that a normal layer of soil will often keep them from germinating.