How the Side-sliced Cutting Came to Be
By G. G. Nearing
The appearance of a number of papers dealing with treatment of rhododendron cuttings by wounding is very gratifying to me, I am happy to note that the real and important purpose of the wound has not gone entirely unnoted. For when in 1939 1 originated this device, it was to fill a special need. The fact that at the same time it promoted and speeded the formation of roots was an unexpected bonus. Most of those who write on the subject have concentrated on this secondary benefit, and Mr. Wells does not even mention that there is any other.
Years before the appearance of Bulletin 666 (which by the way, Mr. Wells, was published in London before it appeared in New Jersey) I had trouble with my rooted cuttings, particularly of 'Caractacus', always my leading seller. They had a tendency to put out one small root from the callus, then grow the whole root system as an extension of that one. If small plants were once tipped over, which often happened because the slender junction between stem and root was flexible, the wind would keep blowing them this way and that, pressing the soil away from them until there was a funnel-shaped opening all around, which no additional roots could jump. The only remedy was to cramp them with three diagonal canes, and keep them that way for a year or two, after which new roots would grow strong enough to serve as an anchor.
About the same time Mr. Skinner came out with his method of growing leaf-bud cuttings, which I adapted immediately as an adjunct to my own system, and although the percentage of strike was lower, and the plants took a year longer to reach selling size, there were ways in which it was helpful to me. When I saw how readily roots formed along the cut surface of the leaf-bud cutting, I couldn't help wondering if they might not do the same thing if I made a similar cut on the stem cutting. One trial convinced me, and after that time I side-sliced all cuttings. I did not keep this method secret, but explained it to some of my friends, and when Warren Baldsiefen took over my method after the flood, he too sliced all his cuttings. The method we used was exactly as illustrated by Mr. Wells. I was interested in his statement that he learned it in Belgium in 1946, because the news must have spread rapidly to travel so far, and in only seven years.
It came as a surprise that experimenters have had good results by side-slicing the stem on both sides, and by stripping. At first I tried similar methods to see if there would he any improvement, but the cuttings mostly died. No doubt the difference lies in the speed of rooting. When the roots form quickly with heat, there is less chance for the invasion of fungi and rot bacteria, than with my slow method of rooting cold.
I soon saw that in the trimming of most of my stem cuttings, I could take a leaf-bud cutting from the side of each, and in so doing, give it the side-slice without additional cuts. Thus from nearly every tip I get two cuttings, a leaf-bud cutting and a stem cutting. Even though the success with the leaf-bud cuttings is much less in most varieties than that with the stem cuttings, they take less space, and so are a help. Those which root seldom fail to grow on, though often belatedly. Destruction of the dormant bud is probably caused by heat in the propagating house.
And here let me say a word about forcing cuttings with heat and drugs. Did you ever try to sell a forced azalea back to the grower who forced it? He knows the long time that will be needed before it recovers from the forcing, and believes that it should be thrown away in favor of a new plant. If intended for growing in the open afterward, there is even less chance for the forced plant.
How does a rhododendron know that in the terrible heat of August it is time to begin hardening the wood for protection against frost? Scientists have various answers, no single one of which tells the complete story. It requires all of several stimuli to promote the changes in a plant that will enable it to meet the hardships of the coming winter. One important factor is the established rhythm of the season cycle. An alpine rhododendron will bud up in June because the summer has already lasted as long as could be expected on a mountain top. When no cold comes, it will often shed those buds, grow a while, then bud again, and even again later when autumn really comes. From its heredity in the seed, this alpine measures the time between the last frosts of spring and the expected first frosts of autumn. Or how else can we explain its actions.
Woodland rhododendrons expect a longer summer, but not one starting in January. When you upset the natural cycle of the seasons with hothouse heat and light, whether you are forcing a plant for Easter or forcing a cutting or graft for profit, the plant is thrown out of its stride, and cannot immediately fit itself back into the natural cycle. If the propagator really considers his customers, shouldn't he hold the same opinion of a forced cutting or graft that he holds for a forced Easter plant? It should be hardened with the greatest of care, and nursed along for at least a year, until it recovers from the forcing, re-establishes in its makeup the natural cycle.
I believe that a plant propagated in the natural cold of the season is a better plant in its first two years than one forced along by heat. It will take much longer to root, and will not be nearly as big, but it will know its way around the seasons. When people stop paving for plants by the inch, they will get better plants, and more will live.