Gentian seeds are germinating in two weeks with GA-3. I dissolved a pinch of GA-3 in about 1/4 cup of water. I surface-sowed the seeds, and carefully watered them in with a fine mist. I then applied GA-3 to the surface of the potting mix with an eye dropper. The containers were then covered with clear plastic, and placed 6 inches under cool white fluorescents, at roughly 60F. Don't go too much warmer than that. G. sceptrum, calycosa, puberulenta, and clusii are germinating strongly now. I can now grow them on under the lights until April, at which point I will transplant them and place them in the cool greenhouse.
Sorry, I can't provide an exact concentration of GA-3.
As usual, a large percentage of exchange seed is dead. Zero percent germination doesn't leave much to the imagination. GA-3 will not resurrect dead seed. If you really want the plants, get seeds from several different sources. I recommend Alplains, Gardens North, and Jelitto for viable, correctly named seed. Jelitto is not cheap, but their seeds grow. I still have a lot of seed in the freezer from the Robinetts and Ron Ratko, and it still germinates well.
If you've let your seeds lie around in a shoe box for 15 years, you really shouldn't send it in to the exchanges. It's dead after about 2 - 4 years. On the other hand, if you freeze seed at 0F in an airtight container, it will stay viable indefinitely, 20 years or more in my experience. Never expose seed to temperatures above 100F, like in a closed car on a summer day. Seeds are a lot more perishable than you might think.
Here is a good link about Gentians and GA-3: http://www.gentians.be/index.php?page=articles&art=3
He likes to sow them in April, but I think that's way too late. You will end up nursing very tiny plants into the hot summer months, and Gentian seedlings do not like high temperatures. Losses are high. If you sow them in midwinter under lights, you will have sturdy little plants by Spring, that you can transplant into individual pots in the greenhouse, or (if you are very brave) directly into the open ground. Remember that Gentians hate root disturbance, so do not damage the roots or let them dry out when transplanting. Keep the roots covered with moist potting mix at all times.
The European alpine Gentians, like acaulis, clusii and dinarica, do not like to grow in temperatures above 50F or so. You can germinate them under the lights at 60F, but if you try to grow them there, you will lose them. I moved them out to the cold greenhouse as soon as they germinated. They seem to be doing well. Once they develop true leaves, they can stand higher temperatures.
Gentians are difficult plants, so don't get discouraged if you fail with them. Keep trying.
Gentiana sceptrum seedlings, sown 12/21/12:
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From seed collected on Larch Mountain by Faith Mackaness in roughly 1985, and stored at 0F since then.
Gene when you make this solution and apply it with an eye dropper how many drops do you use per pot and can you save the solution for later (how long) and perhaps for other seeds which require GA-3
This is what they look like this morning:
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Arie, I apply roughly 36 drops in a 3.5 x 3.5 inch pot. It's enough that every seed will be exposed to GA-3 on the soil surface. I have not done a lot of testing to find out the best concentration, the best application rate, etc. I just don't have time. If something works for me, I keep repeating it. I have not tried the filter paper method, because I don't want to handle the seeds more than once.
You need to water the pot BEFORE you apply the GA-3. If you water heavily after you apply GA-3, you will wash the GA-3 deep down into the soil, and it will not be absorbed by the seeds which are at the soil surface.
Also, once most of the seeds have germinated, you need to apply a weak solution of balanced soluble fertilizer. Otherwise, the seedlings will not develop, and will eventually die. For lime-loving plants like Gentianopsis and Physoplexis, I also give them a light dusting with dolomite lime. Never let the seedling pots get dry.
This is an excellent reference for non-technical people who want to use GA-3: http://www.jlhudsonseeds.net/GibberellicAcid.htm
And they also sell it. But I don't use any of the stuff that they send, except the GA-3 and the eye dropper.
Quoting from the Hudson notes: "Solutions of GA-3 are said to break down with time or exposure to sunlight, so store in a dark place. Kept in the dark it stores for years. We have tested solution stored at room temperature for 4 years and found it fully active."
I store the solution in the fridge, which of course is dark. But I don't take chances with old solution. I always add a little more GA-3 powder to my stored solution. I don't have any problems dissolving it, even though the solution is cold. Even though my method is very sloppy and inaccurate, the results are excellent. If somebody has time and facilities to do comparison trials, it would be valuable.
I am currently using GA-3 to germinate Gentiana, Gentianopsis crinita, Gentianella detonsa, and Physoplexis comosa. It's working well on all of them. But I think the trick is to use GA-3 combined with fluorescents and propagation domes at cool temperatures. Now you eliminate all of the stresses and risk factors. The seedlings can safely develop during the first few weeks when they are tiny and vulnerable.
I am considering using Gibberellic acid on Gentiana acaulis, and also on some Trillium seed as well. I'll likely follow Gene's formulation, at least for Gentiana acaulis. Deno advised that GA3 is recommended for recalcitrant Trillium seeds. Has anyone tried using it on the genus? The seed from the exchange arrived dry packed, so I suspect that a treatment might help shake them out of deep dormancy. The seed is already planted, so I'd have to follow the eye dropper protocol. Should the solutionbe made stronger than for the Gentians?