Rhododendron: An ornamental flowering shrub, native to five of the seven continents and also one of the most common detrimental words in a spelling bee. For many gardeners and landscapers across the United States, the month of June is the celebrated season when these delicate yet striking flowers bloom. A distant cousin of the earlier blooming Azalea, these deciduous woody shrubs showcase vibrant flowers for about two weeks before shedding their festive petals to boast only their waxy green leaves for the remainder of the year. While the rhododendron comes in several varieties and is often a staple item throughout the backyards of America, these treasured plants need to be most cared for in the following months after they bloom.
It’s no wonder that these popular woody shrubs are described as hardy. Growing anywhere from tropical climates such as the rainforest to more harsh landscapes such as northern Canada and Eastern Europe, rhododendrons are tough and dynamic. While all 20 plus varieties of these plants are strong, there are a few things that New York gardeners will have to look out for, especially during the unforgiving summer months.
Because the roots of these shrubs are shallow and tend to vein through on the surface of the garden bed, it’s easy for them to dry out, specifically in July, August and September. Throughout the summer, water your rhododendrons frequently; however, don’t overdo it as root-rot (destroying the root by over-watering) is the second most common way to kill these beautiful plants (number one is awarded to those who forget to water altogether!) A good idea to avoid major drought is to surround your rhododendron’s roots with a generous layer of leaves or mulch. This protective layer will retain moisture in the summer and prevent frost damage in the winter.
While water damage is the number one killer of rhododendrons, spider mites win the silver prize. A common parasite on many indoor and outdoor plants, these tiny “gummy” looking pests are only noticed under close inspection of the plant. Because rhododendrons are usually planted in partial shade, these mites might not destroy this species as severely as they would a plant which requires full sun or an arid atmosphere. Getting rid of spider mites can be quite the difficult task; however, one usually successful technique entails misting the plant with 1 part rubbing alcohol and 1 part water. Because alcohol will evaporate rapidly, especially during warm weather, it will poison the mites without damaging the leaves of the plant. In extreme cases when this homemade concoction won’t suffice, a carefully selected miticide should be used with caution. Safer soap is a recommended miticide for any garden pest as it’s biodegradable and safe for plants.
A frequent and noticeable aesthetic detriment to rhododendrons is that of iron deficiency. This ailment is marked by leaves which are heavily drooping and yellowed. To correct this issue, one must mist the plant with a chelated iron fertilizer. In addition to targeting the leaves themselves, soil enriching elements such as ammonium sulfate or sulfur should be incorporated into the soil to renew proper Ph levels. For most plants including rhododendrons, appropriate Ph levels for the soil should be between 5-5.5.
As the rhododendron season comes to a climax, enjoy those beautiful blooms and be sure to deadhead once flowers have fallen (this can sometime ensure a stronger bloom the following year). For those who are missing out on these attractive flowering shrubs, contact us to see how we can help incorporate these festive plants into your outdoor space. Requiring little yearly maintenance, we carry out effective ways to plant these trees both in function and design. By using drought resistant soil components and diagnosing specific plant types to both soil and light exposure, our friendly landscape design architects will have you enjoying this blooming season for many years to come.