The best time when to trim fountain grass back is in the late winter or early spring. The exact timing is not as important as just making sure that you prune fountain grass back before it starts actively growing. You want to avoid doing fountain grass pruning in the fall, as the plant has not yet died back all the way.How tall is fountain grass?
Fountain grass plants may get two to five feet tall, in a clumping habit. The arching leaves that radiate from the center of the plant give it its name. Mature fountain grass plants may get up to four feet wide.How to plant fountain grass?
To grow fountain grass, plant it from nursery transplants or seeds sown directly outdoors after the last expected frost. If growing from seed, water the soil frequently to keep it evenly moist. Plant fountain grass in an area that gets full sun for best results, although it can tolerate partial shade.