QBARS - v24n1 Increasing Rhododendron Enjoyment

Increasing Rhododendron Enjoyment
Ted Van Veen, Portland, Ore.

My remarks today will buzz through rhododendron propagating; hit a little more heavily on field growing with application of culture techniques for the homeowner; and finally I will tell you what a wholesale grower can do to spread the rhododendron gospel throughout the land. This last area calls for further explanation and justification for presentation to such a group as you. This will be covered as I proceed with my remarks.
I come before you as one perhaps somewhat apprehensive because my rhododendron experience is relatively short as compared with many of you. Neither my schooling or past experience was in horticulture. My entire career, until the time of my father's death, was centered around IBM machines. Nor am I particularly mechanically inclined. I just sold the system - I didn't have to repair the equipment.
However, do not misconstrue my apprehension as lack of confidence. I have a conviction. Almost all of my waking hours in taking over my father's business have been devoted to the rhododendron. Love increases with knowledge. The more I learn about rhododendrons, the more I love them. I am thoroughly convinced that there is nothing quite like a rhododendron, and I am sure that you feel the same way. We all share rhododendrons with our friends in exchanging plants, cuttings, perhaps some seed or seedlings, or even a beautiful truss from a favorite plant.
Our nursery is in business today primarily because we like rhododendrons. We believe in rhododendrons, at somewhat of a risk I might add, to the point that it is our exclusive crop.
I am here to share rhododendron knowledge with you, and perhaps from these brief remarks today you will glean a few ideas, which will help you do a better job with rhododendrons. and which you in turn will be able to pass on to others.
With this background, I hope you will understand better my motives for this talk and that you will forgive any commercials which might be implied.
The majority of our cuttings are taken from large stock plants which receive special care for this purpose. A particular fertilizer program is maintained, overhead watering is freely used, flower buds are removed prior to opening, root weevil is controlled and aphid invasions are checked religiously.
The best cuttings are those with the most vigorous shoots and flower buds. These cuttings will have strong axillary vegetative buds which will break into well-branched plants with the first flush of growth the following Spring.
Rhododendron cuttings are taken the latter part of June and the operation continues, based on rooting-experience records, through early August. Generally there is a history of poor rooting for cuttings taken after this until about the middle of September. More cuttings then may be taken until January. However, the overall percentage of rooting is less for this period.
Strong cuttings will produce a good root ,system, the key to a well-grown rhododendron. A powder is used with Captan as a rooting hormone. The cuttings are grown in open benches under mist with bottom heat in six inches of peat moss and perlite. This depth allows for excellent drainage.
The cuttings are removed as rooted and transferred to beds of pure peat with no feeding and very little water through the winter. Gas heaters are used to keep the temperature above freezing. Under these conditions, the bed becomes a mass of roots.
In February, the heat is turned up. Now it is time to water, foliar feeding starts and the pinching begins. During this time a constant vigil is kept for possible development of botrytis, root weevil, chewing insects, aphids, or anything new which might harm the crop.
In June, the liners are Wilt-Prufed and moved to the open field with overĀ­head irrigation. Some bark dust or raw fir sawdust is tilled into the clay soil. The fields are tiled to assure absolute drainage. No mulching is used in order to reduce possible frost damage. General fertilizing is held off for a month or so until the roots have started to take hold in the new medium.
At this point, I would like to say a word about rhododendron container growing. I am not an advocate, not only because of the hazards and additional care in feeding and watering which this involves, but because the finished quality of plant never is quite up to par as compared with a field grown rhododendron. However, there are some varietal exceptions, primarily in dwarfs. Root bound conditions inherent in containerization, coupled with the expansion and contraction of the container in hot and cold weather, does not seem to be the ideal situation for the fibrous roots of a rhododendron. It is true that modern marketĀ­ing of plant material dictates the need for a container, but this can be handled by transferring the field plant a month or two before shipment, because the rhododendron root system will become established quickly.
During the two and half years the rhododendrons are in the field, they are receiving much TLC in the form of pinching and pruning. Weeds, insects and diseases are controlled chemically.
The shaping of a plant during this period requires expert knowledge. For adequate formation of flower buds, feeding and watering, with due allowance for changeable weather conditions, necessitates good judgment on the part of the commercial grower. Un-budded rhododendrons are not salable. The overhead irrigation also is used for early and late frost control.
The current year's crop is dug in the Fall. Approximately 25% of the crop is held out as non-salable because of faulty shape, breakage in digging, poor foliage color, or insufficient buds. The best of these are reset for sale the following year and the remainder go to the brush pile. The root balls of the finished plants are shaped and burlapped. Then they are removed to a heeling-in area, graded by size, labeled and placed in sawdust to protect them until shipment.
I believe that one of our greatest problems with rhododendrons is the lack of understanding with regard to the root system. To keep freight costs within reason, and also to prevent the root ball from being torn away from the stalk because of weight, the roots are trimmed back in the digging operation. By the same reasoning, plants grown in a container are almost always tightly root-bound. It is absolutely necessary to break this mass by cutting and tearing before setting out in the garden.
The soils used by the grower will always be different from that of the homeowner. First of all, this will result in watering difficulties. Water does not easily flow from one soil type to another. Plants grown in clay, for example, if dry when planted, will have difficulty ever becoming wet throughout the entire root ball. It is necessary to soak such a root ball in a tub of water until thoroughly drenched. Using a jet spray, wash away some of the soil to expose the root tips. In this way, they will be in position to take off readily in the new surrounding. It is not necessary to tamp down the earth around a newly transplanted rhododendron - watering-in will settle the soil sufficiently.
As you probably realize, most rhododendrons are lost by planting too deeply. Insufficient drainage is another root problem and, of course, this encourages the water molds, such as Phytophthora . We should realize also that if we are unable to get enough water into the root system, the plant will not take up fertilizers. To help the public succeed better with rhododendron purchases, a pack of instruction cards on planting and care goes out with every order.
Another major problem is lack of buds. This is mostly due to overzealous feeding and watering, and too much shade. Sometimes rhododendrons prefer a little neglect. Some hybrids, such as those with R. griersonianum blood, cannot tolerate much fertilizer. I am reminded of a foolish situation on my part. A couple of years ago, I was in Los Angeles and noted that the Rhododendron 'Emasculum' did well under their alkaline water conditions. I brought one plant back with me and because it was still in the winter months up north, I placed it in one of the benches in the greenhouse. In a few months it was dead. I was not thinking when I planted that rhododendron which apparently thrives under higher alkaline conditions, into the extremely acid peat moss in the greenhouse.
In the interest of helping the home grower better understand how to be successful with Rhododendrons we have used a number of approaches. First of all, membership in the ARS has been encouraged through our catalog. Since this catalog is widely distributed, it has stimulated interest in many new areas which heretofore had little knowledge of rhododendrons.
Rhododendron books, including the ARS publications, are an excellent means of educating the pubic. These also have been spotlighted through our catalog. A couple of years ago, we used Dr. Clarke's excellent book, "Getting Started with Rhododendrons and Azaleas" in a promotion to stimulate new sales. Unfortunately, the publisher ran out of books before our season closed. Our catalog carries a list of recommended rhododendron publications.
While on the subject of books, for some time I have felt that there is a need for something in good color which will illustrate the more commonly used varieties - something which garden centers and homeowners can use for reference. Surely, such a book would attract thousands of new rhododendron enthusiasts and acquaint many of the moderates with new ideas. I am working on such a book which, hopefully, will be out for Christmas. It will not be highly technical but it will be a "how-to-use" book, stressing landscaping and which Rhododendrons are best in the more difficult areas of the country. There will be approximately 200 colored pictures. Every effort is being made to produce a useful, top quality book - one which every garden lover will be proud to own and display.
I have tried to tell you a little bit about what we are doing to make rhododendrons more enjoyable for you. If I have succeeded, then I am happy.