Gibberellic Acid

March 18, 2009

Sorry, for the repetition. I posted this before in the wrong place.

Has anyone tried using any Gibberellic Acid on any of their orchids? What did you use it on, did you dilute it, what were the results?

I'm thinking about trying this but my orchids aren't getting enough light so I'm not sure that it's a good idea until I put them outdoors for the summer.

Then stitzelweller responded:


I tried GA extensively on a wide variety of orchids back in the Dark Ages. I had absolutely no detectable response!

As I vaguely recall, the concentration was ~ 18mg/gal of 10% GA in a powdered form. 90% is also available however, it's just too concentrated (and co$tly!) for experimental use by a hobbyist. I can understand using the highly concentrated GA when applying from a crop duster across a soon-to-ripen crop.

I know that my GA was good. It worked on other plants, as expected (tomatoes, beans, etc) in the concentration described above. Maybe, orchids need a higher dose?

I have read (but don't really know) that if AOS Judges get wind of GA being used on flowers to be judged, they get very miffed. Something about deception. In my case, I didn't know where to find AOS judging back in Olden Times!

What is your GA source? I need to get some fresh stufff!


Comments (11)

  • lunaticvulpine

    heya Stitz

    I recently got done with some GA experimentation
    Turns out from my own experience foliar applications and soaking are the best ways to introduce the solution though I've notice if you use undiluted solution on new growth i has a tendency to cause tall spindle like growth

    also you might try the united nuclear site as they sell a 100% GA solution at a good price.

    depending on your goals you might just look into keiki pro as i've had some very interesting and reliable results


  • ms_minnamouse

    United Nuclear has it as a liquid, so how can it be 100%?

    I found another site that has it for a great price, and at 90%. This site also has easy to understand instructions for mixing the ppm that you want.

    JLHudsonseeds also has it at 90%. They sell it separately or in a kit.

  • lunaticvulpine

    true. i see you point, perhaps a call to verify the concentration?

    personally I think i need to look for some thing to counter the lanky growth habit as that tends to make the subject quite anemic


  • stitzelweller


    Thank you for the links.


  • kauserzi_gmail_com

    Recently i tried GA 10ppm on my orchids and it had a devestating effect. all the leaves wilted and now in the middle of the season i am stuck with no flowers. how can i revive my plants any solution please let me know.

  • terpguy

    Gaston, I dont think you can counter it. Gibberrelins are primarily responsible for internode elongation of new shoots so when applied that should be one of the first responses you notice.

  • stitzelweller


    please, check your reference.

    this is the header for the last time that Gaston posted on this thread:

    Fri, Mar 20, 09 at 0:01


  • terpguy

    LOL my how threads resurrect! *eep*

    Kauser, theres really not much you can do, the damage is done. At this point its a matter of waiting. The good news is that, provided your plant survives the excess GA will eventually be metabolized. It won't fix the damage done. Keep caring for it as you normally would, watering when it dries out, etc...and if it survives it should eventually return to normal.

  • stitzelweller


    Your 10 ppm seems very concentated. When I successfully used GA on my vegetable and non-orchid flowering plants, my target concentration was 1.8 mg GA per gallon of water - far less than what you used. While I never had any success with orchids at that concentration, I grew some other tremendous plants!

    I never experienced any "toxic" effects from the use of GA. What was your reference to use 10 ppm, please?


  • David.Sturtz

    The generally recommended dilution for gibberellic acid ranges from 250 to 1000ppm. 1000ppm is too strong for some plants so I usually avoid solutions above 750ppm
    One gallon equals 3,785ml, so for a 1000ppm solution 3.75 grams would be needed, so 1.8 or 1.9 grams would be about right for 500ppm. A slightly rounded 1/2 teaspoon of 90% gibberellic acid in a gallon of water would give you about 500ppm. Both Amazon and eBay have inexpensive gibberellic acid.

  • HU-512806798

    After reading this last night, I used a slightly rounded 1/2 teaspoon of gibberellic to a gallon of water on my new Hazelnut trees. They were all fine this morning except for the one and it's leaves were wilted so I let about 10 gallon of water trickle on the roots and it came out of it. I think 500 ppm will be a strong but safe dillution for my young trees,and thank you for doing the math David.

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