The rhododendron sports large, dark evergreen leaves all year. In the spring months of March, April and May, the shrub produces an abundance of pink, white, purple, burgundy, orange and yellow blossoms. There are over 850 species of rhododendrons available, and numerous hybrids. Sizes range from 1 foot in height to over 100 feet for some varieties. Planting can take place any time of year in a mild climate. Spring planting is ideal in areas that have cold winters.
Rhododendrons prefer acidic soil conditions with a pH of 6 or higher. When soil conditions are too alkaline, agricultural sulfur or ferrous sulfate works well as a soil additive to increase its acidity, according to the American Rhododendron Society. Adding organic matter, such as peat moss or aged manure, at the time of planting will help add nutrients to the soil.
Choose a location that offers wind protection. Rhododendrons are susceptible to leaf scorch from ongoing windy conditions. Their delicate bark is also easily split from heavy winds. Filtered sunlight and partial shade are ideal. A rhododendron can grow in full shade, but its flower production will be dramatically reduced. Avoid full sunlight, which will bleach both the evergreen foliage of the shrub and the blossoms.
Loosen the root system of the rhododendron prior to planting. Simply work the roots and the soil with your fingers after removing the shrub from the container. Loosening the roots and soil helps the root system spread into the nearby soil easier. Dig a hole that is twice the diameter of the root system. Plant the rhododendron at the same depth the shrub sat within its container. Planting a rhododendron too deeply can kill the plant or seriously stunt it.
Rhododendrons enjoy moist soil conditions. Water the newly planted shrub thoroughly. Apply 3 to 4 inches of mulch around its base. Peat moss, bark chips, pine needles or leaf debris works well. Mulch will help the soil retain water and will keep the weed growth around the plant limited. Refrain from fertilizing at the time of planting, according to the University of Missouri.
Watering the Root Ball
The root system of the rhododendron is slow to spread out. It will often remain compact in the root ball for up to a year. This makes the root system highly susceptible to drying out. The roots of the rhododendron will not tolerate extended drought periods. Keep the soil moist around the plant, but do not allow it to become water-logged. Water the newly planted rhododendron using a slow-dripping hose, so the root ball becomes thoroughly saturated. Weekly watering is required to establish the shrub.
The newly planted rhododendron does not withstand excessive heat. When the temperature rises to above 95 degrees F, mist the plant's foliage. On cold or exceptionally windy days, misting the shrub will help keep the shrub's evergreen foliage in perfect condition, according to the American Rose Society.