Seeds (achenes) of fringed sage were collected in central Saskatchewan in 1987, 1990, and 1991, and studies were conducted to determine the effects of imbibition time before brief or prolonged exposure to red (R) and far-red (FR) light on germination. A majority of the seeds required light for germination, but a substantial proportion germinated in darkness. Phytochrome controlled germination, and its activity was influenced by the duration of imbibition and by seed collections. At least 8 h of imbibition were required before phytochrome was activated by R light. The stimulation of germination could be reversed by FR light, and this suppression subsequently could be reversed by exposure to R light. Variable light requirements for germination of fringed sage can be met following large- or small-scale disturbances or in relatively undisturbed conditions.

Seeds of fringed sage were collected in four different years in the Northern Mixed Prairie and placed in sealed vials in the field for up to 5 yr. The seeds were exhumed monthly and incubated at 10 or 20 C in light or darkness. Germination was greater at 10 than 20 C and greater in light than darkness. The overriding influences of light and temperature generally decreased as seeds aged. No well-defined dormancy/nondormancy or conditional dormancy/nondormancy cycles were revealed. Longevity of seeds varied among collections, ranging from 3½ to more than 5 yr. Patterns in germination of different collections were similar when they experienced the same annual changes in temperatures, indicating that germination of previously buried seeds of fringed sage was regulated by temperature. This regulating effect varied among years of storage; germination either increased or decreased with increasing temperatures, or was not affected. Results suggest that fringed sage seeds can germinate and emerge anytime during the growing season if temperature and moisture conditions are suitable. Continuous germination may enable fringed sage to occupy safe sites as they develop over time.

Experiments were conducted to determine the influences of temperature, light, winter storage, and water stress on seed germination of fringed sage. Seeds collected in 3 yr in central Saskatchewan were placed in sealed vials and buried in the soil after harvest, and germination was tested in spring and early summer. Seeds germinated over a wide range of temperatures with alternating 25/15 C being optimal. The range of optimal temperatures was higher for older seeds than younger seeds. The stimulating effect of light on germination varied among collections and incubating temperatures. Total germination and germination rate was limited by water stress and no seeds germinated at osmotic potentials below −0.9 MPa. Seeds hydrated in the autumn and exposed to low winter temperatures had higher germination the following spring than dry seeds exposed to the same conditions. Results suggest that sufficient soil moisture combined with moderate seedbed temperatures are optimal for fringed sage germination. Periodicity of germination may be influenced by variable germination requirements in different aging seeds.