QBARS - v15n4 Rhododendron Notes

Rhododendron Notes

Some plants of Rhododendron macrophyllum were still blooming in July on the Olympic Peninsula. This member of the clan sometimes scorns the humid and moist conditions generally associated with rhododendrons and grows instead in quite arid places in company with Arbutus menziesii, Arctostaphylos colunibimia and Vaccinium ovatum. An attractive texture combination, it occurs in a "now you see it, now you don't" manner after crossing the new Hoods Canal floating bridge on highway 99E on the way to Pt. Townsend or Pt. Angeles and again on highway 101 as it skirts the bluffs high above Discovery Bay and the Straits of Juan de Fuca on the way to Pt. Angeles.

- Ruth Jacobson, Seattle, Washington

We are about halfway between seasons and it seems to be an appropriate time to do a little checking on the past year's plant performance before time distorts our memories.

The past summer has not been kind to the Rhododendron enthusiast. We had a May temperature of 105 degrees in Oakland and San Francisco. In addition, the summer has been characterized by periods of high fog and cool weather between periods of weather much hotter than normal. Amateur growers have experienced much trouble and annoyance.

The hot spells required many extra hours of watering. Leaf burn was bad in most locations. With some plants the new growth was completely burned off while with other plants the old foliage suffered heavily. A few people had plants burn so badly as to require cutting back to the base and there were a number of plant losses.

The detailed experience in my garden in Oakland may be of interest as it describes conditions that existed in many other locations. Die-back necessitating unusual pruning was more prevalent than usual, a few of the worst were: Rh. spinuliferum, 'Countess of Sefton', 'Oregon Queen', 'George Bitter', 'Tally Ho', tephropeplum. Leaf burn was very bad on spinuliferum, davidsonianum, nuttallii, ciliatum, tephropeplum , 'Bustard,' and 'Lucy Low'.

We have had more premature bloom this September than usual. I wonder if we should blame the weather. R. 'Elizabeth', 'Sapphire', 'Max Saye', racemosum, aberconwayi and elliottii which is showing color on a few burls, most astonishing.

Second growth while occurring on some plants every year seems to be more pronounced this season. R. 'Royal Flush' (pink), 'Ruby Bowman', 'Ivery's Scarlet', 'Forsterianum', 'Veitchianum', 'Elizabeth', 'Unique' and ya kushimanum of all things.

The plant losses in our garden were extensive but it would not look well to place too much emphasis for our failures on our "Glorious California Weather" out of consideration for the sensibilities of the Chamber of Commerce.

Some died because of too mild and warm a summer for high altitude plants.

The exceptional weather probably affected others. Phytophthora, always prevalent here, had a hand and lack of requisite cultural requirements finished off others. However, the list is jolting: glaucophyllum, haematodes, 'Lucy Lou', concatenans , augustinii (2 plants), carolinianum , kyawii , cinnabarinum , neriiflorum .

This loss of "hard to obtain plants" is offset by the very fine growth made by many species and all of the old hardy hybrids. We have a very fine bud set and look forward to a good season.

The maddenii without exception grow well and fast and are not affected by weather changes or heat provided those that burn are not out in full exposure, although a few stand full sun. The Knaphills are doing extra well.

In reviewing the above it seems to be of more historical than cultural value. However, many may find consolation after reviewing my plant tragedies?

- Edward H. Long, Oakland Chapter

Two or three days after the Conference last May the temperature here jumped from the 80'S to the 90's, not at all good for rhododendrons. Many plants were in soft growth and in exposed situations burned badly. The summer has been hot and dry with more burn reported than any year We can remember. The heat and dryness has been particularly hard on new plantings especially when rhododendrons were moved in late spring just prior to the heat of summer. Plants with roots not well established were particularly hard hit. This would seem to indicate that there are many advantages, in climates where summers are hot and dry, in fall and winter planting. Roots become well established over winter and plants go into summer heat in better condition.

Removing burned leaves from plants helps prevent fungus diseases. Rhododendrons will promptly replace damaged leaves and if we have a fall growing season without severe early frosts plants should look well by spring.

At a recent meeting the discussion was upon species. The question was asked what is R. wardii ? After having raised eight or ten forms under different collectors numbers, we were surprised how variable it can be in leaf size and growth habit. Some years ago plants such as R. astrocalyx and R. croceum were merged with R. wardii . The form of R. astrocalyx we are acquainted with is an open growing plant, but shapely, with leaves of medium size but not like other forms of R. wardii we have grown. We raised a number of forms of R. croceum , some with quite convex leaves. We have seen R. wardii with leaves 2" long and some with leaves nearly 6" long. Flowers will vary in size and shape and in markings. While these plants may now be grouped to suit the botanist, it is certainly most difficult for the buyer. You may see a good plant of R. wardii in a friend's garden and want one like it. But if it does not have a variety name how can you be certain of what you will get? We have never seen a poor form of this species. All plants from reports we have read, are good. But there is even a white form reported.

The answer to this problem, not only with R. wardii , but with many other species, would be to follow the suggestion of a visitor to the Conference from England. Select the good forms of species which we have and give them variety names. The best form of each variety, so far as can be determined, should be given an award.

This difference in a certain variety, in some cases, can be so extreme that the amateur grower cannot understand it. For example R. tephropeplum we formerly recognized as a small leaf dwarf with good habits and small dainty pink flowers. We had R. deleiense with much larger foliage and flower. Now, they have been merged with no variety name to distinguish between them. And, more we have a Kingdon-Ward form collected in Burma in about 1953, with a still larger flower and some plants have a deeper color. Some plants from this collection are very dwarf growing, others quite tall.

A group of plants in the A. C. U. Berry garden, grown from collected seed under the name R. lepidostylum , is most interesting. They caused many comments from visitors to the garden during the Conference. About a third of these plants are the typical R. lepidostylum , low and tight growing with gray-green leaves and stems which are very hairy, which we know in this country. Part of the remainder retain the typical leaf and stem color but are tall and open growing. Their growth is at least twice as much as that of the dwarf plant. Another group has lost the gray-green leaf color and the hairiness. They also are tall and rather open growing, rather resembling small growing plants of the Triflorum series. But, all these plants have practically identical flowers, in size, color and shape. And, all of them have better colored flowers than the "pale yellow" listed in the RHS handbook. The question is are these plants forms of the same species, R. lepidostylum , or are some of them natural hybrids? If they are hybrids, why are the flowers practically identical? What could the cross be to give flowers similar or identical to the dwarf form which we have accepted as being typical of this species?

Above are just three species where confusion exists. There are many more. If species are to become popular, and their popularity is constantly growing, good forms must be selected and given variety names to assure the buyer getting what he wants. It is just as important as the selection of a fine clonal form of a hybrid.

Important to rhododendron growing in this country; the many visitors from abroad made us appreciate more the many good forms of species we are growing and our good new American hybrids. And, just as important, their comments helped us weed out plants which were poor.

We like to grow clematis with our rhododendrons. We think they are grand vines and even have them growing up posts in the lath house. But, we do not use lime and have found by experience that good clematis can be grown in this country without its use. In fact our clematis gets exactly the same treatment, fertilizer and all, that the rhododendrons get. And, they like it. We will not advocate the use of lime in gardens where plants are predominantly acid-loving. Many gardeners often move plants about to change the garden scene. Lime use would present a problem.

The California Horticultural Society, in April of this year, published a 100 page Rhododendron Issue of their Bulletin; the best small booklet on rhododendrons we have read. We have often thought the Rhododendron Society should have a booklet of this type for sale at shows and available for new members who are just becoming interested in rhododendrons. This booklet does a good job of covering the entire field, and is well illustrated.

In writing, in the above Bulletin, on the west coast native R. macrophyllum , Dr. Elizabeth McClintock states that the white form has been recorded as being collected only three times. One other time was noted in the Bulletin of the American Rhododendron Society, some years ago. About 1942, Mrs. Bovee found a plant of this just north of Florence on the Oregon coast. As it was in land being cleared we were given permission to dig it. We still have the plant although it was badly damaged in the freeze of 1955 and is not in good health. A plant or two was turned over to the U.S. Forestry Service at Mt. Hood. This white form blooms about two weeks later than the pink form and has a very fine. just a hair-line of pink around the outer edge of the petals.

- Bob Bovee, Portland Ore.