Is there any reason I cannot/shouldn't cut some ornamental grasses down to half of their height right now? They grasses are located in islands within the sidewalk of a strip mall. When it rains the grasses all flop over and lay all over the sidewalk (run off from the roof lands on them) I want to cut them down to about half their height, for the rest of the season? Is there any plant health reasons not too? I live in MI btw.