This is just a general guide to troubleshooting dormancy problems that may arise when you are trying to germinate seeds of varied species.
Give Me Your Fresh Seed!
Generally the belief is that you want nice fresh seeds that have matured fully on the adult plant, you don’t want old seeds at all, nothing over a year in storage; THIS IS NOT ALWAYS THE CASE (!), there are many dormancies that seeds can have and older seeds of some species will have a much higher germination rate when given the proper treatment. Even some tropical species germinate better after a few months than when just picked off the tree. Some seeds WILL need to be freshly harvested, one that comes to mind is Neem (Azadirachta indica), whose seeds dry out in a period of 1-2 months after harvest and must be planted within this time frame. Therefore you need to understand what your specific seed requires for germination, do your research either on our webstore or throughout the internet.
Dormancies are methods of seeds to delay seed germination to periods of suitable conditions that will favour young plants. If seeds drop off a tree and germinate under the tree before being carried off by an animal, wind, water, ants, etc. this is not good for the parent tree and for the species in the long term. They prefer to be dispersed. Dormancies are complex and varied but include;
~ physiological (basically the seed requires a cycle of low and high temperatures to germinate, this is called stratification. There are several levels of this dormancy. Gibberelic Acid (GA) can help to break certain types of these dormancies.
~ morphological (the embryo is underdeveloped and needs a period of time for full development before germination can take place)
~ morphophysiological (a combination of immature embryo and a physiological dormancy)
~ physical (ie. the seed coat has a very hard seed coat that water cannot get past, stopping germination until this barrier is weakened by penetration, abrasion, heat, etc)
This is only a basic view of seed dormancies, a good site for all aspects of seed biology is ‘The Seed Biology Place’ (http://www.seedbiology.de/)
Some examples of our seeds with dormancies
Acacia spp. Acacia have a physical seed dormancy, use hot water treatment or scarification to allow water penetration and seed germination process. Some alpine species also appear to have a physiological dormancy, like Acacia alpina.
Lagochilus inebrians This species has a physiological dormancy; they need 3-6 weeks at 4 degrees Celsius or below before germination can take place, often we find they will germinate in the fridge. It also responds well to GA treatment at 500-1000ppm.
Agryreia nervosa Physical dormancy, nick the seeds and soak in water overnight allowing water to enter the seed and the germination process to begin. This also applies to Ipomoea, Merremia and other Convolvulaceae, though they will be variations amongst this large family!
Psychotria spp. Psychotria have a morphological and and physical seed dormancy, P. viridis takes a long time to germinate as the seed needs to fully mature and the hard seed coat to imbibe water for germination.
Duboisia spp. You can germinate seeds of Duboisia spp. when fresh without treatment, once they fully dry out for storage they enter a physiological dormancy. GA treatment of 500-2000ppm will override this dormancy.
There are many more, but we hope to have sparked your interest in this fascinating field and you experiment with your new order of seeds from Herbalistics!