How to Care for Old Rhododendron Shrub Plants


Rhododendrons are hardy shrubs that bloom in showy pink or purplish flowers in spring and bear deep green, leathery foliage year round. Rhododendrons are low-maintenance evergreen shrubs that require almost no care when they're planted in a native or otherwise appropriate climate. Old rhododendrons usually have fewer care demands than younger, newly planted ones, because they've already become well-established in their environment. Older rhododendrons usually have more pruning requirements, however, especially if they've been neglected for a number of years.

Step 1

Water your rhododendron deeply and evenly once each week during the spring and summer, only in the absence of rainfall. Water the rhododendron in late fall or early winter one time if the fall season has been especially dry, but don't water the shrub during September or October to allow the rhododendron to harden off for the winter.

Step 2

Spread a 2- to 4-inch-thick layer of heavy, coarse mulch, such as wood chips or bark, on the ground over the root area of the rhododendron shrub. Add more mulch each year in late fall to keep the layer to the desired thickness.

Step 3

Feed your rhododendrons once each year in early spring with a slow-release fertilizer made for acid-loving plants. Apply no more than 2 pounds of fertilizer per 100 square feet and follow the instructions on the label.

Step 4

Prune your old rhododendron shrub to remove all old, dead, damaged or crowded growth immediately after the shrub finishes blooming in late spring or early summer. Cut away all branches that are growing inward or touching the ground. Remove the flower stems as soon as the flowers fade.

Tips and Warnings

  • Don't leave the soil dry in late fall, because this will harm the rhododendron and cause sun scald or leaf scorch during winter. Ensure that the soil around the old rhododendron is evenly moist and stays that way in November and into the first freezes of the cold season.

Things You'll Need

  • Garden hose
  • Coarse mulch
  • Slow-release acid fertilizer
  • Pruning shears
  • Iron sulfate or agricultural sulfur


  • University of Missouri Extension: Growing Azaleas and Rhododendrons

Who Can Help

  • Caring for Rhododendron
Keywords: grow rhododendrons, old rhododendron care, rhododendron shrub maintenance

About this Author

Sarah Terry brings 10 years of experience writing novels, business-to-business newsletters, and a plethora of how-to articles. Terry has written articles and publications for a wide range of markets and subject matters, including Medicine & Health, Eli Financial, Dartnell Publications and Eli Journals.