Plant of the Week
The Easter freeze of 2007 was a traumatic event in my garden with the azaleas especially hard hit. But, amongst them was one plant, the PJM rhododendron that was unfazed by the assault of the out-of-season, 17 degree Fahrenheit weather.
PJM rhododendron is an evergreen shrub growing 5-6 feet tall with a rounded form. The leaves are 3 inches long, smooth green in the summer and purple tinged to bronze in the winter.
PJM is functionally sterile, so it never sets seeds but instead spends its energy reserves producing flowers. It’s the earliest of all the azaleas and rhododendrons in my garden, usually blooming in early April and about two weeks before the first azaleas. The blooms are produced in a fist-sized truss at the ends of the branches.
To appreciate this plant, you’ve got to appreciate purple; something the color purists seem to scorn in gardens. Some critics have described the bloom color as a "dirty, squalid lavender-pink," but I appreciate the color because it kicks off the blooming season for my shade garden. And the plant is an ironclad, growing from Alberta, Canada throughout the coldest parts of the upper Midwest and New England to the southeastern states.
This rhododendron owes its existence to the political upheaval that plagued Europe during the early part of the 20th century. Escaping the turmoil, Peter John Mezitt was a Latvian who immigrated to the Boston area and opened a nursery in 1923. The nursery, Weston Nursery, has always been a family business and remains in operation today under the direction of the founder’s great-grandson.
In 1939, Peter’s son Edmund, had just graduated from college and was working in the nursery when he spotted a rhododendron in bloom in one of the greenhouses. The plant was Rhododendron dauricum var. sempervirens that had been sent to Edmund’s father by missionaries living in the Altai Mountains in the border country between Mongolia, Russia, China and Kazakhstan. The plants were a gift, thanking him for the $50 donation to their cause.
Ed took pollen from the extremely cold-hardy Central Asian plant and pollinated blooms of Rhododendron carolinianum, the native rhodie species that ranges down the Appalachians from Virginia to northern Georgia. Seeds were harvested, planted and then lined out in a nursery row for evaluation. They first bloomed in the spring of 1945 and on the spot, the son named them for his father.
The nursery sold these seedlings under the name "PJM," even though there was slight variation in color and plant form. Some plants labeled under that name have a more pinkish hue while others have a more purplish cast. In the 1960s, the nursery selected the best clones of these seedlings and began propagating them vegetatively. The PJM rhododendron offered today is most likely one of these called "PJM Elite."
Rhododendrons have a reputation for being difficult to grow but this isn’t the case with PJM. It does best with an acidic (pH 5.2 – 5.5), highly organic, well drained, but never completely dry soil. Fresh pine bark mulch mixed with an equal volume of sand and then tilled into the top few inches of topsoil makes a good planting medium for azaleas and rhododendrons.
It does best in an area receiving bright sky light or light filtered shade. While careful adherence to growing conditions are musts for many of the fussier rhododendron hybrids, PJM is more forgiving and has considerable drought and freeze tolerance. It has excellent disease and insect resistance.
By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - April 18, 2008
The University of Arkansas Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.