i have found java fern to grow very well above the water line with out any problems, in all cases i started in one of two ways, either i just pulled a small plantlet off a leaf and placed it onto a branch then draped a small piece of java moss over it to help hold it in place, the plantlet did wilt and dry up within a day or two, but after another 2-3 weeks it started to grow and i had no problems with the new growth drying out. the other way i have grown it was to break off a piece of the rhizome about an inch and a half in length and place it or wedge it where i wanted it to grow, again after a couple of weeks away it grew, here is a pic of some java fern growing above the water in my tank, it has probably doubled in size since then and i have taken cuttings from it too.
here is the link to the post with my tank, it has been running since the begining of last year so you can flick through the pictures and get an idea of the growth rate of the different plants, the faster ones were removed over time and the anubais and java fern are now the dominant plants in the tank
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