About seed dormancy

Seed dormancy is a natural process which prevents seeds germinating until the conditions are optimum for successful growth. Some reasons why seeds remain dormant are:

  • To prevent the seed from germinating while it’s still on the parent plant.
  • To protect the seed against harsh environmental conditions such as cold winters.
  • To ensure that sufficient space and light is available for the plant to grow (eg light reaching the seed in a woodland setting due to another tree dying, or after a forest fire has killed surrounding plants).

Seeds have several different mechanisms to maintain their dormancy:

  • Chemical inhibitors within the seed coat can trigger and maintain dormancy. The seed may require time for the inhibitors to be worn away or water to wash them away. For example, some desert species have chemical inhibitors to prevent the seed germinating until there has been a rainfall, thereby guaranteeing that the germinating seedling will have access to the water it needs to survive.
  • Hard seed coats which prevent water (and sometimes oxygen) entering the seed and triggering germination. Once the seed coat has been worn down (by damage, passing through animal’s digestive systems or soaking in wet soil) germination can begin.
  • Physiological (immature embryo) dormancy prevents germination of the seed until certain environmental conditions (usually related to temperature) are met. The environmental conditions allow the seed to ‘after-ripen’, a developmental stage prior to germination. This is often a protective strategy to allow the seed to survive the harshest extremes of temperature in a dormant state.

In order to overcome seed dormancy, you need to understand what is causing and maintaining the dormant state and what, therefore, is required to overcome it.