Stratification
/ˌstrætəfəˈkeɪʃən/
Definition
Stratification is a seed treatment and natural biological process in which seeds are kept under specific moisture and temperature conditions, most often cold and moist, for a set period to break dormancy. It imitates seasonal conditions such as winter, allowing internal chemical changes that prepare the embryo for germination. This distinguishes it from scarification, which weakens a hard seed coat rather than changing dormancy through temperature and moisture exposure.
Use in Gardening
- Breaking seed dormancy: For many temperate trees, shrubs, and wildflowers, stratification helps end dormancy so seeds germinate after winter rather than during a brief warm spell in fall.
- Signal of seasonal timing: The process works as an environmental cue. Moist chilling can trigger internal changes in the seed, including shifts in hormones that reduce the effect of germination inhibitors.
- Common in propagation: Gardeners and nurseries use stratification to improve germination in species such as many maples, oaks, peonies, and milkweeds when seeds would otherwise sprout slowly or unevenly.
- Moisture matters: Seeds usually need a moist medium during stratification, not just low temperature. If they dry out, the dormancy-breaking process may pause or fail.
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