The most common cause of ornamental grasses falling over is too much nitrogen in the soil. Once they grow to an overly large size, the sheer weight of the mass of grass blades can cause the entire plant to bend down and fall over.Click to see full answer. Hereof, should decorative grasses be cut back in fall?First Ornamental Grass Rule of Thumb: Cut back warm season grasses in fall or by mid to late spring. If you leave the trimming until spring try to make sure to cut them back to the ground (you can leave a couple of inches) by late spring, before new growth begins.Secondly, how do you split ornamental grasses? for large clumps of grasses such as Miscanthus: cut the foliage to ground level. use a wide-blade axe to hack the clumps into wedges or smaller pieces. pry out. further divide to desired size with pruners. trim away any dead roots. replant and water thoroughly. Regarding this, what happens if you don’t Cut back pampas grass? Sometimes it’s almost too showy — the non-native plant is categorized as invasive in many areas, including parts of California. Pampas grass can also become a fire hazard if left untended. Keep this large plant under control by cutting it all the way back to the ground at least once a year.How do you care for ornamental grasses?Grasses do not need to be cut down before winter. In fact, they are attractive when left standing and the foliage helps to insulate the crown of the plant. Cut back the foliage to about 4-6 inches in the spring before growth resumes. When foliage is removed, spring growth will begin earlier.