My Rhododendron Does Not Bloom

Root Bulbs

• Rhododendrons that appear vibrant and healthy in the nursery have been cultivated under controlled conditions -- from being planted in the correct soil type to proper watering. The environment dictates how well rhododendrons will grow throughout the seasons. Plant new rhododendrons where the root bulb will have ample space. It is important to avoid letting the root bulb dry out, as it may become unhealthy and prevent the rhododendron from blooming.

Soil

• Rhododendron roots thrive and bloom better in light, acidic soil. There are several ways of increasing a soil’s acid levels, including adding fertilizer containing ammonium nitrate to the soil. Mix leaves, pine needles and bark together to create a naturally occurring acidic mix that can be added to the soil surrounding rhododendrons. If you're unsure about the acidity level of your soil, purchase a do-it-yourself acidity test at a local garden center.

Lighting

• Because of the varieties of rhododendron available, it can be daunting to decipher how much sunlight is need during their blooming periods. Most rhododendrons do well in afternoon shade, but if in doubt, ask a gardening expert at a local nursery. Many new shrubs come with instructions detailing their botanical name and sunlight requirements. If rhododendrons are not blooming, it could be due to overexposure to the sun.

Pruning

• Prune rhododendrons to prepare for next season’s blooms by removing all dead branches and clusters in the early spring, if they were not removed in the late fall. This ensures the shrub is not using its energy in a dead section. Removing clusters after they have bloomed helps the shrub prepare for the next season’s bloom. Rhododendrons are slow-growing but resilient, and pruning from early spring through late fall will ensure future blooms are bountiful.

Infestation

• If infested, a rhododendron may not bloom to its full potential. Leaves that leaves are yellow or falling off may indicate an infestation of lace bugs. If the bark is eaten away around the stem's root, weevils may be to blame. Borers, white flies and red mites can also prey on the rhododendron during spring and summer. Prevent infestations by periodically inspecting the bark, stems and leaves for bugs and treating the shrub immediately.