Known for its clusters of violet trumpet-shaped flowers, R. ‘Blue Peter’ is one of the classic American “Iron Clads” meaning it is cold hardy. It has been used in the endless attempt by hybridizers to achieve a true blue large evergreen rhododendron. It is, however, like most so-called blues, not quite blue, but rather cobalt violet at its margins with an almost white throat and purple blotch.
The hybrid ‘Blue Peter’ was raised and named by John Waterer at the family’s Bagshot Nursery in Surrey, England in 1930. Its parentage is unknown, which was not unusual due to a lack of record-keeping by many early hybridizers. It was registered in 1958 by the International Cultivar Registration Authority.
In 1993, the hybrid ‘Blue Peter’ received the Royal Horticultural Society Award of Garden Merit. In 1973, Dorothy Knippenberg won a First-Place prize for her ‘Blue Peter’ rhododendron growing in the arboretum at the annual flower show of the Princeton Chapter of the American Rhododendron Society. It is one of ten named hybrids in the arboretum that were hybridized by John Waterer which the Knippenbergs added to their rhododendron collection. It blooms Mid-Season which is generally the first two weeks in May depending on weather conditions.
Our rhododendron propagation team selected ‘Blue Peter’ for our fall propagation program. Stem cuttings were taken in September from several of our ‘Blue Peter’ hybrids in the arboretum and treated with a rooting hormone and placed in a rooting container in the propagation greenhouse. The rooting container was placed on heating mats to provide bottom warmth of about 70° F to encourage root growth. Laurelwood’s Horticultural Manager, Joan Scott-Miller, purchased several heating mats and thermostat controllers for use by our propagation program and seedling program.