JARS v64n4 - The Ultimate Rhododendron Conference

The Ultimate Rhododendron Conference
Ted Hewitt
Eugene, Oregon
Reprinted from the Eugene Chapter newsletter, May/June 2010

A year ago, Paula and I happened to have lunch with Ron and Carla Knight at the Rhododendron Species Botanical Garden while on a field trip in conjunction with the 2009 ARS [Annual] Convention. As a long-time active member of the ARS Vancouver Chapter, Ron mentioned that he was thinking of sponsoring a teaching conference with limited enrollment at the University of British Columbia Botanical Garden and was wondering if we thought there would be interest in such a conference with ARS members in the Pacific Northwest. Consequently, when we heard last fall that Ron was partnering with Douglas Justice to offer this conference in April of 2010, we thought it would be a good excuse to visit the beautiful city of Vancouver, BC.

The week before the conference was cold and rainy throughout the Northwest and we feared that we would be exploring the botanical garden in our rain gear but, as we drove north from Seattle on a Thursday afternoon, the skies cleared and we could see the skyline of Vancouver with a backdrop of spectacularly snow-covered mountains. To our joy, the clear, dry and relatively mild weather would last through the long weekend. Located on a peninsula jutting into the Strait of Georgia west and a bit south of downtown Vancouver, the University of British Columbia and its botanical garden enjoy a moderate climate with a marine influence.

Friday morning, after the conference introduction, we had a good introductory tour of the UBC Botanical Garden with Douglas Justice, the Curator of Plant Collections, including a brief look at the large David C. Lam Asian Garden and the more exposed gardens to the east that include the E.H. Lohbrunner Alpine Garden. After the tour, we had the rest of the morning to explore the Asian Garden concentrating on the species rhododendrons that do so well in the natural, forested setting of Douglas-fir, hemlock, and cedar trees. Most of the rhododendrons, as well as companion plants, are well-labeled making them quite easy to identify. After lunch at the pleasant restaurant that overlooks the Van Dusen Botanical Garden, we had time to enjoy a bit of the 55-acre [22.3 ha] garden that first opened to the public in 1975 featuring plants from around the world. The current head gardener took us for a tour of the Sino-Himalayan Garden that features species rhododendrons, but in a much more cultivated setting than in the UBC Botanical Garden. It was interesting to note that the smaller lepidotes do better in this colder garden. However, the Rhododendron augustinii were in their prime at both gardens. The Rhododendron Walk of the garden features mature hybrid rhododendrons.

On Day 2, Saturday, the 100 conference participants were divided into two levels, according to their experience with rhododendrons. Level 1 was appropriate for newer gardeners and concentrated on the cultural aspects of growing rhododendrons in the garden while Level 2 included the topics of classification and identification of species, as well as propagation and hybridization. In addition to his role as Curator of Plant Collections, Douglas Justice is also a UBC instructor and researcher and is a very fine teacher - organized, articulate, knowledgeable, and fun - which made for a fine experience with the six sessions over two days.

Session 1, "Douglas’ 25 "Best" Species and How to Grow Them" began with a quick, though concise, description (with pictures) of each of the 25, pointing out little bits of good information. For me, this was a good session for reinforcing what I knew about some of the species and introducing me to ones with which I was not familiar. As would be the case in sessions to come, Douglas wanted to get us into the garden as often as possible, so we also had time to see some of his "Best" 25 as they were growing outside. Session 2 dealt with "The Importance of Soil pH and Micronutrients"; having a good handout made it possible to concentrate on the lecture which was interesting but very much at a higher level.

For Session 3, Douglas and a helper had gathered blooming samples from the garden for us to begin the task of learning to use a dichotomous key for identifying species rhododendrons and using a hand lens to see the scales on the leaves of the lepidotes. For me, this was an exciting event to see, for the first time, not just the scales but the color and different shapes of scales. Working in groups, it was helpful to discuss things like identifying the leaf shapes and flower types and to have the terms begin to make more sense.

On Sunday, Session 4 consisted of a lecture on "Propagating Rhododendrons from Seed or Cuttings," again at a fairly high level for someone (like me) who has done a little propagating with cuttings but without understanding what was happening botanically with the cells of the plant. (Ah, the light is getting brighter!) Session 5, entitled "Ten Common Problems of Rhododendron Culture and Care," had another good take-home handout and was a good time to get us out in the garden to see each of the ten problems in the field and to talk about how to handle the problem. The UBC Botanical Garden has a "no chemical spray" policy so the solution must be organic or environmental. The problems discussed ranged from root rot to vine weevils to nutrition problems to environmental problems - certainly a good session for us all.

The final session, Session 6, "Species Identification," dealt with using the dichotomous key in the James Cullen (2005) book Hardy Rhododendron Species: A Guide to Identification to attempt to identify one or two specimens from the garden. This was difficult due to the size of the group and the fact that there was only one instructor from whom to seek guidance. However, seeing scales and hairs with a high quality microscope was exciting. In the end, I cannot say enough about Douglas Justice as an instructor, the quality of the David C. Lam Asian Garden, the organization of the conference schedule, and the idea of having one quality instructor for all the sessions. It is a different type of format for a conference that resulted from having run a six-week class for Vancouver area people a few years ago.

So what were my favorite rhododendrons? A large R. concinnum covered with purplish-pink blossoms; a brilliant pink ‘Wakehurst’ [parentage unknown]; the beautiful lavender lax truss of R. huianum ; a brilliant red R. thomsonii with a nice calyx; a particularly nice pink, large-leafed R. kesangiae ; a nice yellow R. campylocarpum with a red blotch deep in the throat; and the many forms of R. augustinii .

Reference
Cullen, J. 2005. Hardy Rhododendron Species: A Guide to Identification . Timber Press, OR: 496 pp.