Seed dormancy is a state in which a seed is unable to germinate, even under ideal growing conditions. It is an evolutionary adaptation that prevents seeds from germinating during unsuitable ecological conditions that would typically lead to a low probability of seedling survival. Dormant seeds do not germinate in a specified period of time under a combination of environmental factors that are normally conducive to the germination of non-dormant seeds. Seed dormancy is important for delayed germination, which allows dispersal and prevents simultaneous germination of all seeds. This staggering of germination safeguards some seeds and seedlings from suffering damage or death from short periods of bad weather or from transient herbivores; it also allows some seeds to germinate when competition from other plants for light and water might be less intense.
There are two different categories of seed dormancy: exogenous and endogenous. Exogenous dormancy is caused by factors outside the seed, such as the seed coat, which may be too hard or impermeable to water or oxygen. Endogenous dormancy is caused by factors inside the seed, such as the presence of germination inhibitors or immaturity of the seed embryo.
Seed dormancy can be broken by most ideal growing conditions, which are different and specific for each species. While dormancy can enhance plant survival in the wild, it can prevent seeds from germinating uniformly and growing well in wildflower seed production fields.
