Now that we have had some frost, it time to cut back those perennials and clean them up for the winter. We cut back deciduous perennials when they begin to die back or turn that yellow/brown color in Late October or Early November (depending when the frosts hit). Deciduous ornamental grasses can be left up most of the winter as a focal point until the winds blow them down.
For perennials and grasses that are deciduous, when they die back for winter, we cut them back to the ground. Evergreen or woodier stemmed perennials and evergreen grasses we just even them up and clean out the dead foliage. Some woodier perennials like Lavender can be cut back by about two thirds their size to get them back into shape while others like the Tree Peony are not to be touched otherwise you cut off the next years flowers.
The best way to trim down perennials and grasses is a pair of good hedge shears, for smaller plants you can use a pair of scissors. Then either get rid of the trimmings by either composting them or sending them to the dump. Remember if the plant had some fungal or disease issues during the growing season, do not compost those leaves. It spreads the spores and keeps them around to infect next years foliage.
Here are lists of what to cut back or leave alone