i dont know, thats not much lighting, im running two 48" 40 watt GE t-12 plant/aquarium lights on my 55 and i have japanese moss balls, and some java moss, that is thriving in it. in my situation, the oscar didnt care about them at all. it would pull up my plastic, but it left the real stuff alone strangely... so i just dont have plastic in there, like penn said, its just an algae magnet. since ive moved out the oscar, all thats in there is a lil convict and a bichir, lastnight i moved my 2 GSP's into the tank, we shall have to see how they all get along!

with any luck they wont care about the plants either lol.
from what ive read... ideally... you want about 2.5 watts/gallon for keeping most live plants, any more lighting, usually requires a co2 generator (again, from what ive read).
and FYI, silk plants dont require any lighting at all