That's a good question. I would like to do that but mine usually end up disappearing. Maybe it won't happen now that I don't have cave rock in my tank.
Did they have the ferns attached to anything, or were they free floating?I was at the Newport (Cincinnati) Aquarium the other day, and they had a lot of java ferns floating in the one display. No substrate attachment at all, just like giant duckweed.
Has anyone ever tried this? I have crazy extra java ferns right now, some on sizable rhizomes.