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Journal American Rhododendron Society

Current Editor:
Dr. Glen Jamieson ars.editor@gmail.com


Volume 37, Number 2
Spring 1983

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Don't Fight Natures Ways
Edward S. Rothman, Glenside, PA

       The fundamental principle I follow, and that with great obstinacy, is: Do not fight nature's ways, but be a close imitator of natural systems. Granted, for example, that expensive milled sphagnum moss is a perfect medium for starting rhododendron seed into germination, it is surely not unique. Rhododendrons do not usually occur naturally in underwater swamps where sphagnum thrives. Anyone who collects pine needles for winter mulch must have noticed in scratching deep down for the bottom crumbs, the different texture of the underlying, weathered, half-decomposed, humus-like old needles. These have just the right moisture retention and low pH and do not support the damping off micro-organisms. Where old piles of wood chips rot on shaded grassy turf, the acidic runoff discourages the growth of grass and soft green mosses take over the area. This mossy layer is a perfect culture medium for sprouting rhododendron seed. I sow seed directly on this mat outdoors in autumn and let nature take its own time.
       In cold, dreary Philadelphia wintertime it is satisfying to have a few seedlings started indoors just to have something green to look at. I use a discarded glass aquarium and put a floor of polystyrofoam plastic sheet down and insert 44 square plastic pots atop the flooring. A soft pencil labels the seed lot right on the plastic pot and pots can be lifted and shifted about on an individual basis. A single 15 watt lavender fluorescent "plant growth" type tube is set on top of the glass sheet lid. I sometimes remember to leave the light on all night long, and at 50 degrees F., direct winter sunlight on the new seedlings does no harm at all in this latitude. I resist the temptation to mist the seedlings frequently, but keep a film of water in the closed tank (not touching the pot bottoms).
       Some years ago I "liberated" an old wild R. nudiflorum about ten feet tall from my neighboring woods. I tugged it out by hand without the use of even a garden trowel. In the dense, oxygen-free clay soil overlaid with a layer of rich forest humus, there was no root ball at all to consider - only a dense 2 x 25 pancake pad of fibrous root mass sitting loosely in the detritus. I carried the large but light weight plant in my arms for a quarter mile supporting it with only a torn plastic trash bag. During that walk I had time to consider the habits of these native Pentecosters ("pinxters") and I decided to mimic their growing conditions as closely as I could. After all, these native R. nudiflorums had been in business for a few million years. I figured they must know what they are doing to survive so well and in such large numbers in the wild.
       Of course, I had to make some adjustments because my garden area was at variance with the adjoining woodland. Over the grassy lawn I heaped up scattered crescent-shaped piles of well rotted organic spent mulch - right on top of the mowed green grass - right on top of the foul, un-aerated sculptor's clay that passes for soil atop the mile deep bed rock layer. The general effect is that of a Japanese archipelago with steep islands swimming across the sea that is the grassy lawn. I think of it as an echo-equivalent of a zen-raked, stone garden, or the little islands become, in my imagination, a chain of Antilles Islands leap frogging like stepping stones all the way to the big woods. My little plants - largely Shammarello R. yakushimanum hybrids - are growing little differently from epiphytes in such an organic medium. I use prostrate ground-hugging junipers (Procumbens nana) on the sunny side to tie the pine needles down.
       I find that occasional leaf yellowing is cured by liberal treatments of powdered, gritty dolomite from a nearby quarry. Yes, I know rhododendrons are supposed to like acid soil, but I also observe that published elemental analyses of rhododendron leaf ash always, but always, show a hefty proportion of calcium. Granted I have not isolated the variables of Ca/Mg ratio and effect of moderation of excessively low pH in my unusual medium. I only know that etiolation, that does not respond to chelated ferrous iron or to nitrogen treatments, is often reversed by calcium treatment. For quick action on especially valuable plants I use dilute solutions of calcium nitrate as though I were feeding African violet houseplants (saint paulias). I prefer the much cheaper, much slower acting, "insoluble" dolomite grit. I also use dolomite to put "muscle" into thin, yellowish, fine-leafed Fescue lawn grasses. I deny this is due merely to the effect of neutralizing acid - a principle most lawn experts accept as ancient truth.
       I consider that I do not feed rhododendrons. I feed the micro-organisms living in my mulch blankets and let them feed the rhododendrons by delayed action circuitry. I like the effect of this year's fertilizer not to be felt until a year or two in the future. Insoluble phosphate rock dust can be thrown about anytime of the year. I treat plants ordered by mail very differently depending upon who sent them. I have it easy when I buy from a dealer in Oregon whose mass production cuttings have fibrous root masses (growing in Douglas fir bark) that marry very well into my organic masses. I have trouble with growers who send me plants rooted in perlite-humus mixes. Local colleagues who grow in real genuine honest garden soil have very different results and wrongly suspect the Oregon grown specimens to be un-hardy. Again dense clay root balls have to be planted with extra altitude here or root rot is a certainty.
       This leads to another point that I am sure will cause disbelief in many readers. I find that newly introduced plants to my humid world, reeking as it is with organic decaying matter, frequently get Phytophthora cactorum tip rot the first season. I cut the bad matter away and the plant recovers. That plant is thereafter perfectly immune to that disease.
       To go back to seedlings, I find that the greatest enemy to the safety of the plants is the bird population. Birds looking for worms and insects methodically turn over fall oak leaves in my planting area and usually uproot whole lines of baby seedlings in their hunt. Robins and starlings are expert rhod-i-cides. I have baffled these fine feathered enemies by covering each new transplant with a wide mouthed jar. I dare to put my January 1982-sown seedlings outdoors in summer of 1982. I hill up a few pine needles around the jar to keep squirrels and rabbits from knocking over the jars and to give a slight protection from direct winter sunlight. The jar ends are clean and clear to the overhead sky. The seedlings grow perceptibly in the wintertime and relish the condensed water that bathes them as dusk approaches - when the water is not a film of ice crystals! The plants are observable all fall and winter and the plants are not flattened and killed by dense layers of fallen and wind driven leaves. Best of all, it is easy to locate the planting area the following year. Under these conditions deciduous azalea new transplants are often non-deciduous. Surviving in quite high proportion the 1982-3 unusually mild winter outdoors (say +20 degrees F. night temperatures) were R. calophytum, R. lacteum, R. adenopodum, R. trichophyton and various R. wardii-fictolacteum yellow-crosses "hardified" by e. g. R. yakushimanum or R. catalgla mixings, ditto R. elliottii(giant pink) x R. fortunei (courtesy of H.J. Braafladt via Bill Tietjen's seed exchange packet #679). These last are vigorous growers. (Wish I'd ordered the red R. elliottii cross, too!)
       I use the same jar technique for rooting cuttings. It takes me a lot longer to strike roots, but I haven't space to waste on a Nearing frame and I am unwilling to ruin my fine wood carving sculpture tools with a basement damp area. I find wounding and high humidity are indispensable, but with long waits, hormone treatments are less important. I like to set out cuttings in cold weather (as long as the medium is unfrozen). I feel that low temperatures discourage pathogenic root organisms. When I do use a cold frame I use a wire gauze roof (not a glass or plastic sheet) sprinkled with pine needles to let cold rain penetrate and wet the foliage. In winter time the interior of the rooting chamber can be quite dark. This may or may not be the best way, but it works if you have 2 years to wait. I have learned not to peek to see if roots have started; the plants bitterly resent disturbing. When they finally move, they move fast and leave you in no doubt.
       For a final point, I observe that the old mature 'Catawbas' and 'English Roseums' that ring my property functioning more or less as a screen, repel falling oak leaves which slither over the slippery surfaces and are in large proportion lost to the winds. The leaves are collected by my neighbors from their lawns, are bagged and put out for trash disposal. These I retrieve by the ton and pour wholesale into the interior of the plants in unusually deep layers. The plants respond by spontaneous layering and form dense new root systems. New satellite plants leap frog forward and the new water sprouts form healthier offsets than the parent system, and my screen becomes more lush and a better windshield.
       Apart from new food and humus material carried in from far afield, I seem to have gained the equivalent of an extra zone of temperance, and am able to grow more tender stock than expected for this area ('Loder's White', 'Unique', R. pseudochrysanthum and some Talienses). I may regret these risky subjects since every few decades or so abnormally severe winters can decimate a collection, as happened to the Shammarello's early-on, and to the Washington, D.C. camellia collection last year, but experimentation is the hobbyist's pleasure.
       Where would we Easterners be if C. O. Dexter had not persisted in his folly of using R. griffithianum and the Fortunea group tender subjects for his hybridizing experiments, not to mention the early experimenters who used R. arboreum and R. griersonianum in their hardy hybrids. If it weren't for the iconoclasts we would still be growing only Catawbas, Carolinas and Maximums here. Anyone for Boston-hardy vireyas?


Volume 37, Number 2
Spring 1983

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