Take the lead band off the base of the bunch, and plant each stem about 3/4" apart. In addition to that light, do you also dose fertilizer and CO2? One piece of the equation is no good without the other two. I planted mine about 6 weeks ago and it has doubled in size with 106W over my tank. I recently added another 80 watts, and it seems to have responded well, but I also have a CO2 reactor and dose flourish and KCL every day (my phosphates and nitrates hold nicely without dosing).