JARS v36n1 - Ah! The Propagation of Cuttings by a Tyro
Ah! The Propagation of Cuttings by a Tyro
S. R. Lipsky, Woodbridge, Connecticut
As a long time admirer of the magnificence of the Exbury and Knaphill azaleas as well as their next of kin — the stately rhododendron, I have often pondered over the problem of adding additional members of this clan to my collection without running the risk of imminent bankruptcy. True, I had purchased several dozen plants, at nominal prices, over a decade ago, and reaped much pleasure through the years at what was, in retrospect, a very sound investment indeed. But, alas, today — times, they are a changin' — with all the obvious pressures on the purse strings. This, coupled with the fact that not too long ago, I entered into that dangerous middle aged realm known as the fifties, led to my overwhelming compulsion to be surrounded, forthwith, by a much wider array of these beauties than that in my possession at the moment. After all, the observation that these pleasure domes' often require, on average, a good six to ten years to mature, was not lost on me and continually permeated the deepest recesses of my mind.
Moreover, what a superb heritage for my children and their future children! Undaunted by the folly of one off-springs glib retort concrete to the question, "What would he like to do with this beautiful garden?", I quietly looked to the heavens and praised the wisdom of George Bernard Shaw's comments on the exuberance of youth. And then proceeded with my master plan, with dispatch! It was all very simple. I shall propagate cuttings from those specimens in my garden that I admired greatly and then seek out others whose names conjured visions of instant awesome beauty from collectors near and far by following that old Connecticut Yankee custom of bartering. What followed next, you say? Elementary, my dear Watson, it was sheer disaster!
It would be too painful at this point to detail all my mistakes. What I could do however is to assure you that the term all would have to suffice until a more incisive one came along! Shades of glory turned to despair as hundreds of cuttings succumbed to my lack of knowledge and foresight. My humility soon turned to anger as I hastened to the back issues of the American Rhododendron Society as well as to the various bibles' written by the experts. Much to my astonishment, many of the answers to my problems were to be found here, but lo and behold, no one tome placed the proper emphasis on what I, in hindsight, considered all of the essential details for an amateur to succeed in this particular sphere of endeavor.
About this time, with my morale here at a very low ebb, I had the very good fortune of meeting two septuagenarian plantsmen extraordinaire , Henry Fuller, of Easton, Connecticut, a collector and devotee of native azaleas, and Bill Tompson, of Stamford, Connecticut, a gentleman of the highest order, with an extensive collection of rhododendrons and azaleas. The tides of fortune changed in short order, as information gushed forth from this well of experience. What now follows is the culmination of only two years of experience propagating the usual varieties of Exbury and Knaphill azaleas as well as the hybrid rhododendrons but with yields approaching 75-85 percent. It should, however, be placed in proper perspective, and considered to be one of many methods found to work.
Obviously, there are those varieties whose cuttings still defy rooting, and many questions still remain about the optimal time to take cuttings, the proper concentration of rooting hormone, the status of the plant prior to the utilization of cuttings and the like. All of this not withstanding, I should now like to describe, in the limited space allotted, those general procedures that were established which I found as an amateur to be most helpful in plant propagation.
The timing of cuttings: Here in the Northeast, the different varieties of English azaleas bloom in our garden from about May 21 to June 10th. Cuttings are taken within 2-3 weeks after flowering, at a time when the new growth is beginning to show signs of firmness and the 'hair' on the stems is very ample or dense.
Rhododendrons(Hybrids): Here, my experience is limited to the late Fall or early Winter. Cuttings were taken on a bright sunny day when the temperature was over 40° F. during December to February. Generally speaking, despite some inconveniences encountered with the care of the plants after rooting (in 2 to 6 months), a higher yield rate was noted with those taken later rather than earlier in the year.
Handling of the cuttings prior to planting: Azaleas. The terminal rosette of leaves was always removed. A cutting was always made directly above a set of leaves. On occasion, when a long stem was encountered, 2 to 3 cuttings were made from the same stem and distal and proximal segments were duly noted. Cuttings usually contained from 2½ to 4 leaves. Rhododendrons: Cuttings were made directly above a node, at an angle. The leaf bud was allowed to remain intact. A sharp knife or razor blade was used to slice through the cortex and cambium layers encompassing the entire bottom 1-1½ inches of the cutting (in contrast to slicing both sides). Again, depending upon the size of the leaf, 2½ to 3½ leaves were allowed to remain.
Hormone powder: All azaleas, regardless of color or variety, (see list below) were dipped into Hormodin #2 and the excess tapped off gently prior to insertion into the rooting media. After surveying the literature, I found it to be an exasperating exercise to attempt to correlate the success or failure of rooting to the appropriate concentration of rooting powder or to a particular variety or color.
Rhododendrons: All varieties (see list below) were treated in a similar fashion with Hormodin #3.
The rooting media: Consisted of approximately 65% coarse peat moss and 35% Perlite. Clumps of peat moss were broken up by hand. To each level bushel basket was added a handful of lime and the material was thoroughly mixed in a wheelbarrow.
The container for the media: I started with the typical wood containers used to house varieties of fruits. The sides were drilled to accommodate the usual clothes hangers which were cut to maintain a Quonset hut shape for a polyethylene covering. Although very cheap and portable, the presence of fungi in the wood and potential drainage and aeration problems made me seek a bit more sophisticated and permanent type of arrangement. The following is a description of the housing which I have found to be very versatile in many of the phases of the rooting of cuttings and their aftercare. Other concepts, embodying the same principles should be equally effective.
It consists of a crib shaped rectangular box, 24" x 48" x 10" high whose sides and bottom were constructed from perforated metal (opening ¼ to ¾") for excellent drainage and aeration and fastened to four metal angle legs so that the bottom of the container is elevated 6 inches from the wooden table upon which it sits. A simple thin rectangular frame made of redwood is placed on top of the legs which extend 6 inches beyond the height of the container and fastened with black tape. The metal container was painted with a nontoxic paint to prevent rust.
A piece of 6 mil thick polyethylene slightly longer and wider than the container is stapled into place on a plywood table. The container is then placed on top of the plastic. Before fastening additional polyethylene into place, the rooting media is carefully placed into the container to a depth of 8-9 inches. The amount that spills out of the perforated bottom is negligible. If fine peat moss is used, one can place a single sheet of newspaper on the bottom of the container. The medium is then thoroughly wetted down, one day before planting. It is essential to determine whether or not the bottom few centimeters of peat moss-Perlite mixture has been thoroughly wetted. A pipe cleaner or a match stick inserted from the bottom gives one a clear indication of the depth of moisture. Following this, a piece of 6 mil thick polyethylene is cut in such a fashion that it surrounds the container completely. It is then vertically fastened snugly in place by stapling to the redwood frame on top and to the plywood table on the bottom. The container is now ready to receive the cuttings.
Insertion of cuttings: Cuttings should be taken in the early morning and placed in a plastic sandwich bag and stored in a cool place until placed in the rooting medium, preferably on the same day. (If for some reason, this is not possible, place in the vegetable container in the refrigerator until used) Indentations are made on 2-2½" centers with a clean stick and the cuttings are then inserted. They are firmed into place with gentle finger pressure. Following this, they are thoroughly misted with a plastic hand bottle containing water and a dilute solution (¼ normal strength) of a general purpose fungicide and insecticide. Another piece of 6 mil thick polyethylene which serves as a top cover is cut to overlap the sides of the redwood frame, stapled to the redwood frame in the middle so that cuttings are accessible to examination from either end of the frame. The snug enclosure is now complete and moisture droplets should appear on the inside of the plastic within 24-72 hours.
At this point it should be stated that our cuttings are grown in our basement where the temperature averages 70-75°F, the year around. If no heat is available — bottom heat must be established by the proper placement of a thermostatically controlled heating cable (maintained at 72° in the container) in order for proper rooting of the cuttings to take place within a reasonable period of time.
Fluorescent lights: A fixture containing two 40 watt fluorescent bulbs (one Gro-lite — one plain) is suspended above and outside the container by means of adjustable chains. It was found that the polyethylene does not absorb critical ultraviolet light to an appreciable extent — and life is much easier with the light source on the outside than within the system. If two such containers are established side by side, three fluorescent fixtures (six bulbs) are used instead of two in order to maintain the uniformity of the light source. The fixtures are controlled by a timer that provides light for 16 hours each day.
It was noted, particularly with rhododendron cuttings at the outset some phototropism may occur — where upon the leaves shield themselves from the light by turning their backs to the light. This is corrected by moving the light source an additional 6-18 inches above the container. Under ordinary circumstances, in the beginning, the lights are kept some 6-18 inches away from the tops of the azalea and rhododendron cuttings.
Follow up care: Despite the fact that the plastic container maintains a rather high degree of humidity for the cuttings, we have routinely misted the cuttings (same bottle containing dilute solution of fungicide and insecticide) for a few minutes every 3-4 days. Every 2-3 weeks, the peat moss-Perlite mixture is also watered very thoroughly. After 4-6 weeks, Rapid Gro (¼ normal strength) is added to the bottle mister and the simple routine misting is continued.
Depending upon the variety and local conditions, the azaleas usually show top growth within 8-14 weeks after startup. Within a relatively short period of time thereafter one is able to take cuttings from the cuttings. This we do — not only to rapidly increase our supply but it does encourage branching as well. If a degree of legginess is noted, we open the plastic enclosure slightly — in order to drop the temperature 2-4°F and simultaneously lower the lights by several inches. In our experience, generally speaking, the rhododendrons are much slower in establishing their rooting network (3-6 months plus). For this reason, we find it best to raise the azaleas and rhododendrons in separate containers.
Once the majority of cuttings show ample top growth and the roots are firmly anchored in the medium, the top polyethylene cover is opened gradually over a period of 3-5 days. At this point, if our furnace is on constantly, the bottle misting is increased accordingly, to prevent desiccation. Within a week, the polyethylene cover is removed completely and the plants are allowed to acclimate for an additional 2-3 days. Following this, they are potted in 3" pots containing 50% loam and 50% peat moss well mixed. The pots are watered thoroughly and then placed inside the enclosure on top of the remaining rooting medium and the polyethylene cover once again placed over the container. After 4-6 days, the polyethylene cover is gently removed over a period of several days. During the interim, bottle misting with diluted Rapid Gro is maintained every 2-3 days depending upon the appearance of the plants.
During May, when the possibilities of a sudden frost become remote, the azaleas are placed in the garage for 1 - 2 days and then planted in an appropriately prepared bed in the full sun. It has been noted that when these charmers do receive ample sunlight and water during the growing season, they bud early and with proper pruning — branch readily. Within a few years, mass plantings are a sight few beholders of nature's wonders could readily forget.
Rhododendrons are more partial to light shade — particularly in midday. They are therefore placed in a bed that could be readily sheltered from the wind or sun by the use of burlap stapled onto stakes appropriately located in the bed.
Unless one has been through all of this, it is hard to describe the quiet sense of satisfaction that one obtains when one views the fruits of his labor. Obviously, the enchantment increases astronomically when one can see, over the years, the formation of substantial shrubs from these meager cuttings. It is little wonder then that man in his eternal quest for Peace, welcomes each Spring. It is the time for reawakening, it is the time for another cycle. It is the time, where in a little corner of lovely Connecticut called Wood-bridge, one man, his family, and friends stand in awe when viewing the legacy left to us by the Waterers, the Rothschilds, the Dexters, and other great hybridizers of times not too long ago. These are classics in the truest sense of the word. Perhaps Shakespeare put it best — A thing of beauty is a joy forever! Indeed!
'Anna Rose Whitney'
'Jean Marie de Montague'
'Mrs. W. R. Coe'