Hi all,
I have a lot of Java Fern, and I agree with Pete, in the right circumstances it grows very well under high light conditions. When you buy a "normal" Java plant it is one leaf and very little rhizome, it will take this a long time to grow, and often the plant response will be to produce new plant-lets on the leaf before dieing. If you can get bigger rhizome sections they will bulk up more quickly, but it will never grow very quickly, and really in common with plants like Java Moss and Anubias it is a plant that can tolerate lower light conditions, rather than needing them. I've found the secret with Java Fern is to wait until your tank is well established, buy a "mother" plant/obtain a large lump fasten on somewhere in a bit of current and then totally ignore it.
I have a silica sand substrate, I don't add CO2 or regualr nutrients, keep a light fish load, feed mainly live food and I change a lot of water (10% rain water every day), so this would be a high-light / low nutrient set up, with pH about 7 (during the day, lower at night with more CO2) and KH about 3.
Most fast growing plants won't grow under this regime, it's a bit like growing a lawn, if you feed, mow and water it, you have the "lush, stripey green carpet", but if you stop doing all of this, the grass thins, all the rye grass dies and you are left with a much nicer, lower maintenance area of daisy's, fescue grass, clover and cat's ears
Once low nutrient tanks are fully established, they grow a small amount of green (hair, stagshorn) & red algae(BBA) but all plant growth is nutrient limited, and Java ferns will eventually colonize all the bog wood, rock, sponges etc., older leaves will become algaed, but everything will happen fairly slowly.
cheers Darrel
(low-medium light apps.)