Friday’s seeds with the GA3

I don’t aim to repeat here everything written about the gibberellic acid; most is easily accessible on the wide net. Anyone interested in plants knows that gibberellins are plant hormones which control various processes and the synthetic forms of the gibberellic acid are used in the horticultural industry for various purposes: from seed germination to inducing early flowering, fruit set, hybridization, and so on.

For those who never use it and/or are at the beginning of their growing from seeds journey, I will emphasize a few practical aspects about preparing and using a GA3 solution for home sowing by describing precisely what I do.

First, sources of GA3:  google and you shall find :)
Every year there are various on-line offerings of powder GA3. I do not want to advertise for one source or another, just a warning: if something looks too cheap, it may not be the best quality.

How to use GA3

In powder form – many still employ this method although it is not as reliable as a prepared solution. Personally I don’t use the powder treatment; you cannot be sure of the concentration applied and if the seeds will absorb it equally.
 Nevertheless, it’s easy to apply. One of the most common methods is to place the seeds on a moist folded piece of paper towel or a coffee filter and to add the GA3 (the amount taken on a toothpick tip). Place everything inside a plastic bag and keep it there until next day; then, sow the seeds right away.

Solution – if you want to be sure about the concentration, it is advisable to use it as a solution. The suitable concentrations to promote seed germination vary among different species, and there are still many species for which we don’t know if their germination would be better with GA3.

Many times you just need to experiment. I noticed from my experience and reading lots of articles on seed germination that good results can be obtained using concentrations from 250 ppm to 1000 ppm.

It is not difficult to prepare your own solution: best is to make a basic 1000 ppm solution and then use it as such or at lower concentrations by dilution.

 How to prepare your basic 1000 ppm GA3 solution (assuming you have GA3 98% purity)

The basic stock solution of 1000 ppm (parts per million) is prepared by dissolving GA3 in water at a rate of 1mg (1000 mg= 1 g) in 1 ml (1000 ml= 1 l).

Therefore, if you buy one packet of 100 mg GA3, it will have to be dissolved in 100 ml of water to obtain a 1000 ppm solution; 200 mg in 200 ml and so on….
For home use I don’t think anyone needs more than 100 ml, so let’s do this:

Have handy: your powder GA3 100 mg, 100 ml distilled water (tap water OK too), little amount of alcohol (purest ethanol possible), and a clean 100 ml (or larger) bottle for the final solution. I use the water at room temperature.

Bottle with GA3 solution

Add the powder and maybe ¼ of the water, plus a few drops of alcohol in the bottle and start shaking well; be patient; add more of the water and keep shaking. If the GA3 doesn’t dissolve well, add a few more drops of alcohol; shaking, shaking….20(30) min. should do it.

If after all this the powder has not entirely dissolved it means the GA3 you bought had many impurities.

So you have your 1000 ppm solution.
Label your 1000 ppm GA3 bottle and keep it in the fridge. Don’t forget that this is a chemical substance after all, and it shouldn’t be kept in containers without a clear label. The solution remains active for at least 2 years, probably even longer, but of course its efficacy will decrease.

To prepare a 500 ppm solution, extract any given quantity from the 1000 ppm sol. and add the same quantity of water, all in a separate bottle (don’t forget to label it).

What to treat with GA3?

Think first about what kind of seeds you are sowing and which are their germination requirements.

GA3 is often used to replace the cold period required by various species for seeds germination (cold/moist stratification) and to speed up germination in general.
Therefore, if you live in a warm climate, you are running short of time, or want to speed up the process, you can use it for these purposes.
Warning: it does not always work; don’t be disappointed. For some species even very cold winters won’t do the trick to break seeds dormancy.
Also, sometimes, it is necessary to use a combination of treatments.

For those living in a climate with cold winters, it is much simpler and even better to sow and provide the cold/moist stratification outdoors over the winter.

For Aconitum spp. (and other Ranunculaceae species which have seeds with immature embryos), GA3 has been found useful to promoting embryo growth, so indirectly it will improve germination.

It also comes in handy when sowing older seeds, which may have a lower germination capacity.

There is no point to use GA3 for any kind of seeds. For example, in the case of species with very hard/impermeable seed coats (Fabaceae), using GA3 makes no difference because it cannot be absorbed.

Applying the treatment

Prepare a few small containers (bottle caps, small holders, yoghurt cups…), place your seeds inside and pour GA3 solution on top, just enough to cover the seeds. For larger size seeds, you can also use small plastic bags. I usually leave the seeds in solution until next day.
Important: have everything ready and sow the next day after the treatment; water the pots well, and place at warm or cold as required.

GA3 treatment and sowing the seeds afterwards; sow as usual, next day after treating the seeds

For tiny, fine seeds (Saxifraga for example) it’s more practical to place the seeds on a piece of paper towel, soak it with GA3 solution, fold the paper and keep it in a plastic bag until next day; before sowing, just squeeze the paper towel and then it will be easy to shake the seeds on top of the potting mix. Likewise, a pipette/syringe can be used to collect and distribute the small seeds on the mix.

Side effects: one common side effect is that the seedlings will grow elongated and weak, especially if the concentration was too strong and/or the seed coats remain attached to the cotyledons (in this case cover the pot with a moist paper towel, and you can remove the seed coats after they get soft); Gentiana lutea seedlings after GA3 treatment.

What I am using it for?

I had my share of using GA3 just for fun, like many others probably. Right now I sometime use GA3:

On experimental purpose when reliable germination info is not available and for older seeds to test the germination capacity, especially for small size seeds.

On a more regular base for:

Glaucidium palmatum: there is a bit of controversy in this case and after I have germinated seeds for a few years and also heard other people’s experiences, it is fair to say that this is a species with combined morpho-physiological dormancy: from any given batch, some seeds will germinate at warm, some only after a cold period. I find that with a GA3 treatment I obtain a better germination at warm (but a few seeds will still germinate only next year after one more warm/cold period).

One can easily sow Glaucidium without GA3 in late fall/winter and provide cold/moist stratification; some seeds will germinate in the following spring, some in the second year.

Podophyllum hexandrum – for the Chinese mayapple,  the treatment with GA3 will induce germination with the true leaves, thus speeding up the process; in the second image – seedlings obtained with GA3 treatment in the first summer.

Aquilegia species:  only because I start my Aquilegia species indoors; I use 500 ppm GA3 to promote a good, uniform germination (but you can easily provide Aquilegia with cold/moist stratification and obtain good germination).

Sometimes for Gentiana species: some will germinate well when treated with 500- 1000 ppm GA3 (G. lutea, G. purpurea).

I also got good results for Rhodiola spp., few Thalictrum species (to speed up the germination), Androsace villosa (and subsp. of villosa).

Germinating right now after GA3 treatment and short term cold/dark – Androsace barbulata. I noticed them a bit too late but they will green up under ligths.

Androsace barbulata seedlings

For Aconitum dry stored seeds; some Aconitum species will not germinate after the seeds get too dry, and I am trying to see if/how GA3 can induce/improve their germination; read more and see images: Starting notes on Aconitum germination.

Conclusion: to use it or not to use it?

Keep in mind that GA3 is not a ‘miracle’ solution for all the seeds dormancy/germination related problems.
It is definitely an aid for seeds germination and we can have fun experimenting, but anyone can very well grow plants from seeds without the help of GA3.