Water when dry. Early morning is the best time of day to water. A deep watering once a week (or more in drought conditions) is better than a sprinkle each day.
Deadhead(cut off dead flowers) to encourage repeat blooming. This task is quick and easy, and can as much as double the duration of the bloom time.
Prune back scruffy or floppy plants during the season to encourage fresh new growth. Cutting back to about six inches is generally safe.
Stake or support tall plants like Peonies, Delphinium, Summer Phlox to avoid wind/rain damage. Stake them early, allowing room for growth.
Cut back spend perennial tops in late for or early spring. For the plant it makes no difference. Such plants as ornamental grasses could provide winter interest, while others are best off cut back in the fall to avoid any mold/mildew as the snow cover melts.
Divide perennials when the center of the plant begins to die out. A sure sign of time for division is when the plant, which generally begins growing from the centre point, shows signs of dying in the centre.
Suggestion: Divide spring and early summer blooming perennials in the fall, and late summer and fall blooming plants in the spring. Peonies should only be divided in the fall, while Poppies and Iris prefer early August