Three New Ideas
By Brian Clancy, Melbourne, Australia
Reprinted from "The Rhododendron" with permission of the Australian Rhododendron Society
Tests have proved a simple method of propagating cuttings of Malesian rhododendrons in plastic bags, the removal of the terminal bud from cuttings and the provision of air-vents in plastic pots or containers. The plastic bag method is very simple and should provide the amateur with close to 100 per cent results. All that is needed is clear plastic or, more precisely, a clear polythene bag, sphagnum moss and hormone powder (each of which is readily available at chain stores or supermarkets). The removal of the terminal bud method and the provision of air-vents in plastic pots, should prove to be a big advantage to both the amateur and the professional grower.
These ideas were demonstrated by myself at the March, 1974 monthly meeting of the Society at the Camberwell Civic Centre, and the details are recorded here for the benefit of those who may have missed the demonstration.
The plastic bag method is as follows: Take a piece of new growth three to four inches long that has ripened off. Contrary to past practice, nip out the top or terminal bud. Then trim the scion with a sharp knife or razor blade to a length of about three inches by making a clean cut straight across the base, just below a node if possible. If the stem is of pencil thickness, take a slice of about one and a half inches out of both sides to within one-quarter inch of the base of the scion. However, take only one slice where the stem is half this thickness or less. These slices should extend down to but barely into the wood. Dip the cut portions, sides and base, in Seradix No. 3. Then take a handful of damp sphagnum moss and squeeze between the palm and fingers until the water stops dripping. Tease this moss and squeeze again to remove all surplus moisture. Then wrap this moss around the scion and tie firmly with raffia or string before enclosing with a name tag in a plastic bag.
FIG. 10. Left, cutting has been dipped in Seradix No. 3;
center, wrapped in sphagnum moss; right,
completely enclosed in a clear plastic bag.
Photo by Arthur Headlam
Then place the plastic bag in a warm spot with a good light but no direct sunlight. Incidentally, a cardboard shoe box will accommodate 25 bags.
After about two months, the scion should have good roots and this applies particularly during the warmer months between November and April. In the colder months, it takes a little longer to produce a good root system. Take the rooted cutting out of its plastic bag, remove any surplus moss and then plant both the rooted cutting with the attached moss in an appropriately sized pot and mixture. Leave in a humid atmosphere for two to three weeks and then harden off. At a subsequent monthly meeting one of our more enthusiastic junior members, Steven Moody, demonstrated the very successful results he obtained with his modified version of the plastic bag method. Steven advocated using rubber bands instead of tying with string or rafia, and his modification is a distinct improvement.
FIG. 11. Control plant is in the black pot. "Pinched" plant
is in a white pot which has had air-vents added.
Photo by Arthur Headlam
Now back to the reason for nipping out the top terminal bud. If this bud were left intact, the new plant would generally grow with a single stem and look like the plant at the left of the photograph. However, with the removal of the terminal bud, the new plant generally makes multiple growths and looks like the plant on the right of the photograph. This is the James Wells method as explained by Mr. Wells himself at our 1973 Annual Show Night meeting. James Wells is a world-famous author on plant propagation practices and he is also Executive Director of the world-wide Plant Propagators Society. He strongly advocated pinching the terminal bud of the cutting before being struck and then after each new growth to establish a solid and compact plant. His message was clear and loud, pinch, pinch and pinch!
The air-vents in the sides of plastic pots is another of James Wells' ideas which he stated helped to provide much better plants in much shorter time. As you may well remember, Mr. Jack Wilson showed us many years ago how to utilize plastic ice cream containers by applying a hot poker or soldering iron to melt a hole through the plastic within a fraction of a second. These holes were to provide drainage whilst Mr. Wells' idea is to provide aeration to the roots. I have tested this method since show night and in the short term of six months, I am positive that these vents facilitate and enhance plant growth. The small plastic pot on the right of the photograph has three air-holes made with a hot poker. One of our lady members, Mrs. Rita Hadler, uses the heated tip of a screw driver to provide somewhat smaller holes. In theory, I now prefer a greater number of smaller holes at close to one and a half inch centers. All plants should benefit from these air-holes and none less so than Malesian rhododendrons; the bulk of which are epiphytes that thrive with good aeration to the roots.
Mr. James Wells stated that hormones and wounding are essential if good results are to be obtained. He always uses at least #3 powder but with more difficult rhododendrons, uses powder up to one and a half per cent indolybutyric acid with five percent Benlate added. Where cutting powders are unavailable, he recommended using talcum powder on the cut edges. I always use and recommend Seradix No. 3 for cuttings of Malesian rhododendrons. A small container of Seradix No. 3 costs about 80 cents and is sufficient for 500 cuttings. Write the date of purchase on the can and purchase a new can each year.
Best results are obtained by utilizing those aids and controls conducive to optimum growth, and each of the ideas mentioned fall into this category. Without any doubt, cuttings of Malesian rhododendrons root better and more efficiently with cutting powders. Removal of the terminal bud provides for a better shaped plant with, I believe, an added bonus of earlier growth of the cutting. Air vents in plastic pots are a tremendous aid that increases the already high value of plastic pots.