Established perennial beds add color and depth to the landscape, as they return each year and bloom at predictable times. With careful planning, and planting flowers with varying blooming times, you can create an oasis of color from late spring until early fall. Perennial beds do require routine care to promote vigorous growth and healthy productive plants. Watering, fertilizing, pruning and mulching are the cornerstone of maintaining a perennial garden that creates a show of color throughout the year.
Sprinkle 5-10-5 fertilizer in a ring around the base of perennials in early spring. Follow the recommended application rate on the container. Avoid getting fertilizer on foliage. Work the fertilizer into the soil with a garden claw or hoe. Use care not to disturb the roots of the plants.
Repeat fertilizer application at 6-week intervals until late summer or early fall. Late blooming plants benefit from an application of fertilizer in late summer.
Spread a 2- to 3-inch layer of wood chips or bark around the base of plants to mulch. Mulch suppresses weeds and conserves moisture. Apply mulch to within 4 inches of the plant's stalk.
Water perennials deeply once week to saturate the soil to the root level. Some plants require more or less water, depending on individual preferences, soil condition and weather. Adjust watering as necessary.
Erect stakes or plant supports in early spring. Fences, trellises and plant cages help support the weight of large plants, holding them upright. Use plant ties to secure plants to the supports, if necessary.
Prune or pinch perennial plants before flowering to maintain the shape and size of the plant. Pruning may delay blooming, but extends the season. Check the growing habits of your particular plants (see Resources) before pruning, because some fail to bloom if buds are removed in pruning.
Selectively remove buds to encourage one or two large blooms. Plants like dahlias produce several buds on the same stem. If allowed to bloom naturally, each produces a bloom. If smaller buds are removed, the central bloom increases in size.
Deadhead flowers regularly by clipping off faded or shriveled blooms. This encourages the plant to produce new blooms to replace the blooms you removed. Remove any dead or yellowed foliage as it occurs.
Cut back foliage by several inches after blooms have faded to force a new flush of blooms. Phlox, mums and many other perennials will rebloom if sheared back. The second set of blooms are typically less showy than the first.
Cut foliage back to 3 inches from the ground once it is killed by frost in the fall. Mulch with 2 to 3 inches of straw or leaves to protect plants from harsh winter weather. Remove the mulch in the spring when weather warms and new growth appear.
Divide plants in fall or early spring when they become overcrowded. Perennials typically require division every three to five years.