We have 3 beautiful "Hameln" Dwarf Fountain Grass plants. (Pennisetum alopecuroides 'Hameln'). We're new to grasses, and would like to know when and how much to prune. Right now they are about 16" high and a beige-white color. We live in Zone 5 (Chicago).
Tie the top together and wack it off, then use a weed-whacker to shave it down. I would wait until this cold front moves out, like by next Wednesday, we live on the south side. I lost a couple of nice sized grasses last year because I didn't cut them back far enough, early in the season. They suffocated, according to the folks at Sid's.