|What is the average size of a mature Pennisetum setaceum 'Rubrum'. (Purple Fountain Grass) And what are the suspected chances of it weathering well over an average
|Pennisetum setaceum 'Rubrum' (Purple Fountain Grass) grows to about 4 feet high in a sunny location. It is listed as a hardiness zone 8 plant. Therefore you may find it less than dependable in most winters in your area.
To hedge your bet a little, you could cut the grass back to about 3" high after the first frost and then mulch it with 6 inches or more of leaves or hay.
Northern growers will cut the plant back in fall, pot it up, and store it in a cool area (above freezing, but not too warm) over winter. Keep it barely moist...enough to keep it alive, but not so much as to promote growth or rotting of the plant. In spring, bring it back outdoors and increase the watering a bit. When it is actively growing, set it back into the soil.