Camellias and Gibberellic Acid

    November 03, 2019 11:00 AM | Mike Poole (Administrator)

    About buds: The reproductive (AKA flower) buds are the ones that produce blooms. The vegetative (AKA leaf) buds are usually smaller. 

    • What triggers flower buds to form on camellias? Long days (15 hrs daylight) and warm night temperatures (> 60 degrees). 
    • What triggers buds to bloom? The reverse of above. Temps less than 60 degrees and nights longer than days. There are inhibitory genes that regulate the timing and prevents camellias from producing blooms sooner.  Gibberellic acid (GA3) “inhibits the inhibition” of camellia blooming. There are close to 130 gibberellins, but only four have biologic activity (GA1, GA3, GA4, GA7).

    About ProGibb T&O (turf and ornamental): sold by Valent Biosciences

           - 4% Gibberellic Acid (~ 1 gram per fluid ounce), 95% isopropyl alcohol (toxic & flammable)

           - Recommended for “gibbing” camellias: 2%.  Dilute ProGibb T&O 1:1 with water. However, the undiluted product works great also.

           - Store in “well ventilated cool location”.


           - Select a flower bud with adjacent leaf bud. Twist off the leaf bud and separate it from the cup shaped ring of basal bud scales. 

           - Place a drop Gibb in the “cup”. Consider marking an adjacent leaf. That’s it.


             - Cultivars reported to respond to Gibbing: Arajishi, Christine Lee, Daikagura, Debuntante, Dr. Tinsley, Dr. W.G. Lee, Eugenia Howell, Flowerwood, Herme, High Hat, Lady Vansittart, Margarete Hertrich, Martha Brice, Mathotiana, Mathotiana Supreme, Morning Glow, Mrs. Charles Cobb Var., Mrs. Josephine Hearn, Pink Perfection, Pink Star, Rev. John Drayton, Rosea Superba, Scented Treasure, Tiffany, White Giant, Silver waves, Sweetie Pie. If ypu have good results with other cultivars, let us know and we will update the list.

             - Camellia sasanqua cultivars typically do NOT respond to gibbing.

             - Early and mid-season bloomers tend to respond better to gibbing than late season bloomers. Six weeks is a common interval between gibbing and blooming, although early season bloomers may flower after 30 days. Late season bloomers may bloom in January after October gibbing.

             - Each cultivar has a typical response time to gibbing, with some variability related to the month when gibbed. If you want to produce blooms at specific times (e.g., holidays, occasions, shows), keep records of your individual plants, and their responses.

             - Gibb no more than 20% of reproductive (flower) buds, per year, on small camellia plants. Larger plants are much more tolerant of gibbing. Removing the most distal apical flower and leaf buds on a branch means that there is likely to be no growth or bloom at that site in the next season. 

             - Enhanced growth of the bud can usually be seen at two weeks after gibbing.

             - With a pair or a cluster of flower buds, you typically want to keep and gibb only the one bud that is most likely to have space for the flower to grow without being constrained by adjacent leaves or branches. 

             - You can effectively deliver Gibb to any denuded area of stem near the flower bud, including where other flower buds were or where you might have accidentally removed the entire leaf bud and the basal bud scales. This is especially true if you are using the undiluted ProGibb. 

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