The PJM Rhododendron is an evergreen shrub known for its adaptability and resilience. It displays vibrant lavender-pink flowers in early spring, often before other plants bloom. Its glossy dark green foliage remains attractive year-round, transitioning to a striking mahogany or purplish hue in colder months, providing winter interest. This hybrid withstands severe weather and thrives in windy conditions, making it a popular choice for many gardens.
Planting and Site Selection
PJM Rhododendrons thrive with careful site selection and proper planting. They perform best in partial shade, ideally with morning sun and protection from intense afternoon sunlight. While full sun is tolerated in cooler northern climates, afternoon shade is recommended in hotter regions.
These plants require acidic, well-draining, organic-rich soil with a pH between 4.5 and 6.0. Before planting, amend the soil with well-rotted manure, compost, or leaf mold to improve drainage and enrich it. The planting hole should be as deep as the root ball but two to three times wider, ensuring the top of the root ball is slightly above or level with the surrounding soil to prevent root rot.
Ongoing Care
Watering
Consistent moisture is crucial for PJM Rhododendrons, especially during their first growing season for root establishment. While they need moist soil, avoid waterlogging, which can lead to root rot. After the initial establishment period, watering once a week may suffice unless significant rain occurs.
Check soil moisture by inserting a finger three inches deep; if dry, deep watering is needed. During dry spells, provide deep watering. A two to four-inch layer of organic mulch, like pine needles or shredded bark, helps retain soil moisture and regulate temperature.
Fertilizing
PJM Rhododendrons benefit from fertilizers designed for acid-loving plants. The best time to fertilize is in early spring after blooming.
A liquid acid-based fertilizer can be applied three to four times per year from April through mid-July. Yellowing leaves with green veins indicate an iron deficiency due to high soil pH. Lower soil pH with amendments like wettable sulfur or ferrous sulfate, or use a foliar fertilizer with chelated iron for a temporary solution.
Pruning
PJM Rhododendrons generally require minimal pruning. Prune to maintain shape, remove dead or diseased wood, and encourage bushiness. Prune immediately after flowering in late spring or early summer.
For light shaping, remove the terminal bud from a stem to encourage new branching. When removing dead or diseased branches, cut back to the nearest healthy main branch. Rejuvenation pruning for overgrown plants involves cutting back about one-third of the main branches to one to one and a half feet in early spring, promoting a more natural look.
Winter Hardiness and Protection
PJM Rhododendrons are cold hardy, thriving in various climates. Winter care practices enhance their survival and appearance. Adequate hydration before the ground freezes is important, as dry winter winds can cause dehydration and leaf burn.
A two to four-inch layer of mulch around the base insulates roots against temperature fluctuations. While extensive winter protection is often not needed, safeguarding them from strong winter winds or heavy snow loads can be beneficial in extremely cold or windy conditions. Curling of leaves during cold weather is a natural defense mechanism to reduce water loss.
Common Issues and Solutions
Issues with PJM Rhododendrons are often signaled by changes in foliage. Yellowing leaves with green veins often indicate chlorosis, a sign of iron deficiency due to high soil pH. Correct this imbalance by testing soil pH and amending it to be more acidic with sulfur or ferrous sulfate.
Wilting leaves can indicate too much or too little water. Soggy soil can cause root rot, characterized by mushy, black roots. Ensure well-drained soil and avoid overwatering to prevent this fungal issue. Conversely, dry, curled leaves suggest underwatering, requiring consistent deep watering.
Lace bugs are common pests, causing yellow stippling on upper leaf surfaces and dark, tar-like spots underneath. Repeated infestations can weaken the plant. Manage by hosing off nymphs, using insecticidal soaps or horticultural oils, or applying systemic insecticides in severe cases. Maintaining plant health also reduces pest susceptibility.