Update: GA3 treatment makes no difference for Caulophyllum or other species like it which have immature embryos; they need to be kept moist (or sown fresh) and allowed the required warm/cold cycles, multiple times in case of Caulophyllum (2-3 years).

Speaking about the inside winter gardening, this year I am trying to use GA3 to speed up the germination of Caulophyllum thalictroides (and a few others). There would be much to say about Caulophyllum seeds, from the fact that they develop outside the ovary and have a drupe-like look, they must be kept moist at all times after collecting, to the fact that they have a tiny immature embryo (it’s very hard to see it even with a hand-lens) but a gigantic corneous endosperm…
But I am only showing my new method of treating the seeds with a GA3 solution and then placing them back in vermiculite in the same small plastic bags, instead of using moist towel/Ziploc or sowing in pots. At this point, the embryos are most likely at the torpedo stage.

I think it is a great method for medium to large size seeds and a super space saver (which is of my high interest right now). It is easy to see if/when something germinates, and I had proof that the roots can grow quite a bit on the support they get from vermiculite (in contrast to keeping the seeds in moist towels, where the new roots get entangled and are easily damaged).

If someone is curious to browse the gallery (hover for caption): sectioned seeds/embryos of Caulophyllum, Podophyllum peltatum and of Ranzania japonica, a most intriguing species from the same family as Caulophyllum (Berberidaceae). Many members of this family, which simply fascinates me, are difficult to grow from seeds: think Epimedium, Podophyllum, Jeffersonia, Vancouveria…I will be most happy to grow Ranzania – it looks like a cool hybrid plant between Glaucidium and Anemonopsis!
A few Epimedium and Jeffersonia diphylla were sown early summer last year. We’ll see about that… Update 2017 – the first seedling flowered this year!