Rhododendrons

Rhododendrons are popular landscape shrubs with lustrous, evergreen foliage and spectacular blooms in a variety of colors. Early blooming rhododendrons begin flowering in April while others flower in June. The plants come in a variety of sizes, shapes, and leaf types. This diversity is the result of years of hybridizing between native and Asian species.

Many rhododendrons are indigenous to the Mid-Atlantic and Southeast United States, growing in thickets on the hillsides of stream valleys. This environment contains the ideal growing conditions of bright indirect light, good drainage, frequent rainfall and acidic soil containing plenty of humus. Recreating these conditions will reward you healthy rhododendrons and beautiful flowers.

LOCATION AND PLANTING

Rhododendrons prefer partial shade, but will adapt to heavy shade or full sun. Heavily shaded rhododendrons produce fewer flowers, growing more open in structure than partially shaded plants. Bright, filtered light, under the canopy of tall trees, is the best option. Low tree branches can be pruned to provide early morning and late afternoon sun.

Properly prepared, well-drained soil is essential to establishing and growing rhododendrons. Incorporate a generous amount of Leaf Gro, Super Fines Soil Conditioner, or Peat Moss into the existing clay soil at planting time (1/3 amendments to 2/3 existing soil). If the plant is pot bound, cut the rootball with a sharp knife from top to bottom and loosen the roots. Plant the rhododendron with one-quarter to one-third of the root ball above the ground to ensure good drainage. Mulch lightly on top of the roots to help keep the soil moist and prevent the roots from drying out. Periodically check the soil moisture to see that it is moist, but not wet, and water as needed.

FERTILIZING AND PRUNING

Fertilize Rhododendrons in the spring after blooming and again in the fall with Merrifield Flowering Plant Food 10-18-12 or Holly-tone. Replenish the mulch occasionally to add organic matter and provide nutrients.

Rhododendrons require little if any pruning. If necessary, prune right after they bloom and before the plant sets flower buds in August. Only prune the tender, green growth at the tips of the branches, making cuts just above a leaf node. To rejuvenate an older, overgrown rhododendron, remove half of the stems just above an old growth ring. Remove the other half the following year. Only do this if absolutely necessary, because unlike Azaleas which quickly respond with new growth, Rhododendrons can take many years to recuperate.

Merrifield Garden Center sells over 70 varieties of rhododendrons. The following list shows color, sun tolerance and size of the plant at maturity. If you need further assistance, please see a member of our professional staff.