by Dr. Peter Konjoian
Floriculture Education Services, Inc.
Florel and ivy geranium production fit hand in hand. A total system approach to using this versatile growth hormone channels all of the ivy geranium’s photosynthetic energy into vegetative organs such as leaves and stems which result in fuller plants with more flowers at sales.
The Alpine group of Oglevee ivy geraniums responds exceptionally well to Florel treatment. This group of ivies includes the Balcon and minicascade lines. Balcons comprise 90% of my family’s crop of large hanging baskets of ivy geraniums. Their vigorous habit used to cause problems in production such as long, lanky growth that needed frequent pinching in order to control. This vigor prevented us from growing them in any basket smaller than twelve inches. Three pinches through the winter and early spring months were standard practice to achieve the size and fullness our customers expected from our plants.
It has been almost ten years since I last pinched a Balcon basket thanks to the findings that came out of my research program with Florel. My baskets are easily just as full and very likely fuller than when we pinched them by hand and are produced on a shorter crop schedule than before. This "fuller and faster" effect of Florel at first seems too good to be true. But this is the reality of the beneficial effects ethylene (the active ingredient in Florel) has on a growing number of crops we produce in the commercial greenhouse.
The total system approach to using Florel on Balcon ivy geraniums calls for treating stock plants through the fall months to prevent flowering and stimulate branching. Compared to standard pinching, Florel treated stock plants will produce about twice as many cuttings because of the efficient channeling of photosynthate into vegetative and not reproductive organs. The final stock plant treatment must be made 1-2 weeks prior to cutting harvest to insure there is no ethylene lingering in the cutting at harvest.
Once cuttings have rooted in the propagation area and show signs of fresh shoot growth Florel treatment can resume. Depending on the size of the plug and length of time until transplant one or several applications can be made before transplant. Treatment during this stage of the system again prevents flower initiation and triggers lateral branching. Additionally, ethylene also has the traditional growth regulating effect of inhibiting internode elongation. All of these effects are desirable during this stage of the young plant’s development.
The final stage of the total system is the finished basket. Following transplant, as soon as the plants become established and overcome any shock associated with transplant, treatment can resume. In this final stage of the system the results are the same as in prior stages. Stimulation of vegetative growth which results in full baskets now provides the foundation for increased flowering once the plants are released from the influence of ethylene.
The cutoff date for the last application of Florel to allow for flowering on the desired sales date is six to eight weeks. In the northern U.S. a mid-March cutoff date will generally allow for Mother’s Day flowering. This date varies depending on geographic location and production practices so be sure to trial in your greenhouse on a small scale first. While you are learning how to use Florel on Alpine ivies, or any other flowering crop, play it safe. If a mistake in timing is going to be made make it on the early side rather than the late side. Having the baskets flower a week or two earlier than needed is far less costly than if they flower a week or two late.
Minicascades by definition are more compact than Balcons and common sense suggests that fewer Florel applications should be used. I have found this to be true for finished containers as there is a correlation between final plant size and quality. However, for stock plants and rooted cuttings multiple Florel applications can be used. Compactness in these two stages of the total system are welcome.
Ethylene is a potent plant hormone and a certain level of expertise is required in order to see the beneficial effects described in this article. Negative effects of ethylene can be severe and include stunting, stalling, excessive flower delay, and leaf yellowing. These effects are also associated with misuse of any other chemical growth regulating products. The rule for using Florel successfully is to treat a plant only if it is actively growing. If a plant is experiencing stress in any form exposing it to ethylene will exaggerate the particular stress involved. Plants that are not actively growing are usually under some form of stress. Growers who learn to identify and minimize crop stress will consistently achieve success with Florel on these ivy geraniums. The statement that Florel makes a good grower better and a poor grower worse is a product of this concept of crop stress.
The use of Florel on Alpine ivy geraniums, particularly Balcons, has been responsible for this group of ivies dominating my ivy geranium basket crop. Their outdoor performance is unmatched and now we have a way to produce them efficiently and profitably.
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