Fall is traditionally a time for cleaning up gardens. Normally, we recommend
clear-cutting dead stems to help control insect and disease problems. With
herbaceous perennials that have been pest free, you might want to consider
leaving some to provide structure, form, and color to the winter garden. For
example, ornamental grasses can be attractive even during the winter months.
But those near structures should be cut to the ground because they can be a
fire hazard. Perennials with evergreen or semi-evergreen foliage can provide
color. Of course, some perennials are naturally messy after dormancy and
should be cut back in the fall.
Foliage can be left for other reasons. For example, foliage left on
marginally hardy plants such as tender ferns helps ensure overwintering of
plant crowns. Also, seed heads on some perennial plants can provide seed for
By: Ward Upham