Q.my feather reed grass is turning yellow
I pruned it in March. It came back up great. It is now turning yellow and dying. I fertilized it with Miracle grow liquid. Not a strong mixture. Should I cut it back again or try more fertilizer?
Did the grass receive heavy watering or rainfall in the recent weeks?
Does the grass pull out from the crown easily?
It's possible your plants are suffering from crown rot.
You mention a light fertilizer, which should have been applied in the spring. I would not fertilize again.
Allow the plant to dry out and see if it can recover.