Pampas grass (plumes)
My pampas grass will not bloom any plumes. What is wrong with it? Or what can I do to help it to bloom?
Certified GKH Gardening Expert
Grasses that fail to flower in spite of good growing sites may be exposed to excess nitrogen. This promotes growth of foliage and minimizes formation of plumes. To correct an issue of no plumes on ornamental grass due to too much nitrogen, offset it with some high phosphorous fertilizer. Bone meal is a good fertilizer in this case.
Grasses that are cut back at the wrong time of the year will also fail to flower. For most ornamental grasses, the best time for cutting is in spring, but in milder climates, you may also prune in fall. Do not cut them back in summer, as the forming flower stalks will be removed.
Another factor that prevents flowering is age. Very young starts will not flower until mature. This may be up to three years after planting. Old plants can also fail to form plumes. Much like any perennial plant, flowering slows down as the crown gets old. You may also find that the plant is thinner and grows fewer blades. The solution is division early in the season.