Why wouldn't they grow well in a hex? Do you mean due to lack of light? Java ferns will grow anywhere!! Tie some to a rock or piece of driftwood and you're off to the races. Amazon swords will grow anywhere, too... as will valisneria, ime.
Two things, to have your plant have babies does it just sprot the sides or somethin, and would a java furn be to big for a 10 gallon tank? i have 2 smaller liive plants in there niow and one huge open space
hmm... java ferns have almost negligable lighting requirements under normal tank environments and is under the 'indestructable' category so i would suggest u go for them