Rhododendron Conservation and CollectionsOrnamental Plant Breeding

In progress


Can we develop more ornamental landscape plants that can keep up with climate change?

Our Research

The David G. Leach Research Station has historically been the horticultural arm of HF&G’s research department. The late David Leach was obsessed with elepidote rhododendrons and dedicated his life to breeding and studying them. He gifted the station to Holden Arboretum in 1986 with the condition that we continue his breeding project. Most of the research conducted at the station throughout its history has focused on new plant development.

In David Leach’s time, the focus of the breeding program was on developing ornamentally superior, USDA Hardiness Zone 5 cold hardy rhododendrons. David’s successor, Dr. Stephen Krebs, took the Leach and other hybrids a step further by incorporating resistance to the root rot causing pathogen Phytophthora cinnamomi. Resistance comes most significantly from a Taiwanese species called Rhododendron hyperythrum. For a plant from Taiwan, it is surprisingly cold hardy, but it and its first-generation hybrids do not meet the hardiness standards set in our program. We are just now, more than 15 years after our first hybridizing thrust with R. hyperythrum, seeing the flowers of what we expect to be great new rhododendrons for Northeast Ohio and beyond.

Other breeding efforts will include forays into non-rhododendrons focused on ornamental and adaptive traits. Examples include re- or long-blooming plants for cold climates; sterile, non-invasive landscape plants; plants resilient to climate change; and plants resistant to common or emerging diseases. We use mostly traditional breeding and multi-site field evaluations to make gains in our program.


Rhododendron, Magnolia, ornamental, disease, climate change


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