Seeds could fail to germinate because of their low viability, but that is not the only reason. Most wild species developed seed dormancy as a mechanism to synchronize their germination to the most favorable environmental conditions. They also often avoid germinating synchronously, so that not all seeds would be lost if an unexpected event occurs, thus increasing the probability of the species perpetuating in the natural habitat. That’s why the seeds of wild species often require particular conditions, such as certain temperatures, the absence or presence of light, and other pre-conditions that prompt germination to happen, such as physical scarification of the seed coat or a certain time in colder or warmer temperatures in humid conditions, called stratification.
To understand if the ungerminated seeds are dormant at the end of a germination test, it is a good idea to do a cut test to see how they look inside: are they still looking healthy? If so, dormancy is the likely reason for their failed germination.
You could try repeating the germination test using other conditions or pre-treatments in order to overcome seed dormancy. First, search for existing information in published literature, in Kew’s Seed Information Database or consult local experts or botanic gardens. Then think about the species ecology: Are the seeds dispersed by animals through their gut? Do they germinate after fire or after a long, cold winter? Is there a long dry season in the origin location? Is their regeneration favored by the formation of gaps in the canopy? These questions will help you hypothesize what conditions you might need to simulate in your nursery to mimic nature. These are basic indications to start with, but seed dormancy is a complex topic that needs much more attention. We cover dormancy in our advanced training, currently offered through our Seed to Forest Carbon Accelerator program.
Finally, before spending time and resources in trying to germinate your seeds, it is also important to be sure your seeds are not empty, immature, or infested. If they are, they will never germinate! So you may want to perform a cut test on a sample of seeds before starting your germination test, to assess the percentage of full and healthy seeds. If there is a significant number of empty or infested seeds, you can then adjust your germination samples to account for them, increasing the number of seeds to be tested accordingly.