Challenge The Environment
George Watson, Portland, Oregon
One of my most pleasant pastimes is rereading past issues of the ARS Quarterly. It is like interesting scenery; each time you travel by, something new is seen. So it is with the Quarterly. After reading it from cover to cover when it first comes, and enjoying the articles to the fullest, upon a second or third reading, the thought as expressed by the writer becomes more real. I find this especially true with articles that deal with difficulties of growing rhododendrons in adverse climatic conditions; i.e., what varieties are being grown in some unlikely areas, how to alter growing conditions to better suit rhododendrons in those areas, or simply testimonials of trial and error.
What they all are saying is that if you really want to grow rhododendrons, you don't have to limit yourself to the so-called "Iron-Clads". Don't give up if your particular area has some of these regional problems: hot, humid summers of the South and Mid-Atlantic Coast; the wide temperature variations in the Northeast from extreme cold to hot; dry summers; areas of alkaline soil; and the worst rhododendron enemy of all, Phytophthora cinnamomi (root rot), which exists nearly world-wide and becomes most active when soil temperature builds up.
You probably can grow a far greater number than you ever imagined simply by adjusting your local growing environment as much as possible to suit the plants. First, a little study is necessary to check out the range of plants you could try. Obviously, an R. maddenii in a sub-zero area could be ruled out unless you have a heated greenhouse or a cool plant room in your home. However, hybrids with at lease one of the parents known to be hardy would be worth considering. The back issues of the Quarterly would be an ideal place to start the search.
Some years ago the late Ben Lancaster of Camas, Washington, wrote to the letters-to-the-editor column of the ARS Quarterly about the prospect of compiling a list of heat-resistant rhododendrons and azaleas. A year later a short article by him told of some of the results of his project1. He had heard from various parts of the country on many plants' heat tolerance and was beginning to be able to draw some tentative conclusions. Unfortunately, this was the last of his project.
I would like to pursue this subject and extend it not only to heat-resistant varieties but also to drought-resistant (dry air tolerance) rhododendrons and azaleas. The fact that many are interested in this subject is evident by all the articles that have been written so far. I would enjoy hearing from anyone who has had experience in this: what they have done to grow plants in their area, and what plants they have found to be hardy under their conditions and with their adjusted culture. A list of plant failures would also be of great value. A clearing house of sorts could be set up for information which would be published at a later time in the Quarterly. Although lists have been printed in the past, a new and more extensive listing by climatic zones, which reflects recent discoveries of hardiness and heat tolerance, would be of great value to all who are faced with this ever-present challenge.
1 Quar. Bul ARS 19(2):94