Mitella diphylla germinated today! All seeds were treated with GA-3 on Nov 11.

I don't want to sound completely stupid but what exactly is GA-3 anyway. and what exactly did you do with it. Sorry, it sounds interesting but I have no idea what your talking about.

GA-3 (gibberellic acid-3)is a plant hormone (or the equivalent) which is often used to overcome dormancy in seeds for faster sprouting. From the above he mixed it in a concentration of 500 ppm (that's parts per million) and this would come to 1/20 of 1% or if it were liquid, about 4 drops per gallon.

Many plants will not germinate without some present. A notable one of these is Cornus canadensis.

George

Petunia
one source of info is JL Hudson, seedsman website where you could look up on gibberellic acid info. It is used for some seeds that normally will take long time to germinate or will not germinate at all. For some seeds GA-3 will eliminate requirement for light or cold temperatures/ stratification.
I like growing shade loving plants for my garden and many of rare seeds are toughies to deal with- so I am trying new avenues to see what works.