How to Prune reed sweet grass?
Leaves can be cut back when they die off in late autumn

reed sweet grass · Glyceria maxima
Also known as: leed; meadow reed grass; reed meadow grass
Grow in any reliably moist, fertile soil or in water up to 15cm deep, in full sun. Divide every few years to prevent congestion; can be invasive
Leaves can be cut back when they die off in late autumn