Feather Reed Grass
I planted a Feather Reed Grass four seasons ago and it has done wonderful with full heads. I normally cut it back to three inches in the late Fall, but this year I let it stand and cut it back in March. The grass is full and healthy looking BUT I have very sparse seed plumes...one on one plant, four on another and none on one. This is first time I have experienced this problem.
Lack of seed heads can be from not enough sun, excess nitrogen or that your grass needs to be divided.