Cold stratification generally improves germination of redosier dogwood seed. Other factors potentially affecting germination, such as light and depth of seed burial, were not discussed in the available literature (2012).
In the laboratory, high germination percentages were reported for cold stratified redosier dogwood seed. Seeds stored for 120 to 160 days at 37 to 41 °F (3-5 °C) then exposed to temperatures of 68 to 86 °F (20-30 °C), had high germination rates (80%-90% within 28 days) . In other laboratory studies, seed germination averaged 57% after cold stratification at 36 to 41 °F (2-5 °C) for 60 to 90 days . A regimen of soaking for 1 to 2 days, followed by cold stratification at 36 °F (2 °C) for 4 to 6 months, followed by exposure to a daytime temperature of 75 °F (24 °C), a nighttime temperature of 68 °F (20 °C), and 20-hour day lengths resulted in higher germination rates than other regimens tested . Redosier dogwood seed that was soaked in sulfuric acid and then cold stratified had germination rates about twice that of untreated seed or seed that was only stratified. These researchers suggested that redosier dogwood may have double dormancy and that stratification alone does not result in complete germination .
In studies that compared the germination of redosier dogwood seeds that were kept indoors and those kept outdoors, those that experienced cold outdoor conditions generally germinated better than those kept in the greenhouse. Redosier dogwood seeds collected in northern Michigan germinated better (25%) and faster (in 21-277 days) after 71 to 112 days in an outdoor cold frame than unstratified seeds in a greenhouse (14% germination after 252-510 days) . Redosier dogwood seeds collected from Lincoln County, northwestern Montana, were exposed to a variety of treatments: artificial scarification with sand paper; winter chilling by keeping seeds outdoors in January, February, and March; artificial stratification with refrigeration at 35 °F (2 °C), and artificial heating by pouring boiling water over seeds and then allowing them to cool to room temperature. Germination was best (87%) for seeds treated with artificial stratification. Germination was 69% for winter-chilled seeds, 30% for scarified and winter-chilled seeds, and 20% for artificially heated seeds. The percentage of nongerminating seeds that remained viable after the treatments was 70% for artificially heated seeds, 33% for winter-chilled seeds, and 12% for stratified and scarified seeds .
Although most studies reported that redosier dogwood seed germination improved with cold stratification, Adams  obtained 76% germination of fresh seeds from fruits collected in September. Fruit pulp was removed and seeds were planted in a greenhouse. When the same seed lot was put outdoors, germination was 73%. Germination was 35% for seeds that were dried and stored at room temperature for a year before spring planting .
When researchers compared the germination of redosier dogwood seeds collected for 3 years from 55 natural populations in central and northern Alberta, they found that germinability was strongly influenced by population but that populations with similar germinability could be scattered over a wide area. All seeds were stratified before germination testing. Many populations had germination rates of 80% after only 4 weeks. Seeds produced in the driest year had the lowest germination percentages .
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