Winter is a good time to cut back perennials and bunch grasses. You can cut back some perennials all the way to the ground. These include yarrow, hummingbird sage, goldenrod, California aster, and most kinds of California fuchsia. You can divide other perennials at this time, such as Douglas iris, alum root, seaside daisy, woodland and beach strawberry, yarrow, yerba buena, daylilies, and chrysanthemums.
You can propagate bunch grasses, sedges, and rushes by division this time of year. Examples of bunch grasses are purple needle grass (state grass of California), fescues, blue grama, leafy reed, oat, and deer grass. Some sedges are the meadow, clustered field, and San Diego sedge. Rushes include the common rush and the California gray rush.
More Information: Care and Maintenance of California Native Plants