'PJM' Rhododendron, a hardy Minnesota Shrub - Mickman Brothers Garden Center

‘PJM’ Rhododendron, a Northern Treasure

David C. Zlesak, Extension Educator

Article reposted from the University of Minnesota Extension 'Yard and Garden News' 05/15/2008

Plants of ‘PJM’ rhododendron gracing the entrance of a home. David Zlesak

Flowers and foliage of ‘PJM’ rhododendron are richly colored. David Zlesak

'Olga Mezitt' Rhododendron. John Eustice

Shining in the landscapes of Minnesota and other Northern tiered states for decades, the glowing purple/pink blooms of ‘PJM’ Rhododendron are an easily recognizable and much welcomed addition to the spring landscape. Out of all the rhododendron choices for Minnesota, ‘PJM’ is arguably the most widespread, hardy, and adaptable. Due to minimal or no seed set, it tends to set abundant flower buds and blooms prolifically each year. It performs well in partial shade to full sun and has a wide tolerance to soil conditions, although, like most rhododendrons and azaleas, it prefers cool, acidic, well-draining, soils high in organic matter.

History of ‘PJM’
The name comes from the initials of Peter J. Mezitt, founder of Weston Nurseries in Massachusetts. ‘PJM’ is a cross between two rhododendron species- Rhododendron carolinianum and R. dauricum. In 1939, Peter Mezitt heard of some particularly beautiful specimens of R. dauricum in the mountains of China from some visiting missionaries. He arranged to receive some seedlings and among them was a particularly nice plant that was more faithfully evergreen than the others. Peter’s son Edmund worked at the nursery with his father. Using a camel’s hair brush, Edmund put pollen of the select R. dauricum seedling onto R. carolinianum (this was the first cross Edmund ever made). The seedlings were planted out and a few years later, in May of 1945, Peter and Edmund noticed their spectacular blooms, even as young plants. They knew from the beginning that these plants were very special because of their vigor, compact habit, attractive foliage, and beautiful floral display.

Multiple forms of ‘PJM’ Rhododendron exist
Since seedlings are relatively uniform from this cross, what is sold as ‘PJM’ is sometimes derived from recreating the original cross and raising seed. However, some variability exists among the seedlings for flower and foliage color, growth rate, and plant habit. Selections with unique features have been made and are clonally propagated. Some of the clonal selections include ‘Elite’ (little bit later flowering and more upright than typical ‘PJM’), ‘Victor’ (earlier flowering, more compact, and less vigorous than typical ‘PJM’), and ‘Regal’ (vigorous selection with a spreading habit).
Two other hardy cultivars of note from Weston Nurseries include ‘Olga Mezitt’ (sometimes called just ‘Olga’) and ‘Aglo’. They are similar in growth habit and hardiness to ‘PJM’, but the flower color is more pink. Both are named after Peter Mezitt’s wife, Olga. Both share the same species parents, but differ in the direction of the cross (which species served as the female and which as the male). Just as the cross is reversed to produce each cultivar, so is their cultivar name - ‘Aglo’ is Olga’s name spelled backwards.

*This article was reposted from the University of Minnesota Extension 'Yard and Garden News' 05/15/2008

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