IN FALL: Divide perennials. Every year or two, it's a good practice to dig up and divide certain perennials, like cannas, daylilies, bearded irises, wood ferns, violets and Shasta daisies. These types of plants develop large clumps or bulbs, and dividing them is a healthy practice that allows them more breathing room.
To divide a plant:
• Dig up the plant, being careful to get as much of the roots as possible.
• Gently separate the roots or bulbs, using a hand tool if necessary before replanting your "extra" plants into other parts of your garden.
• Water thoroughly and lightly mulch to protect these new plants and get them off to a good start.