Fruit and Seed
Seed collection: River birch fruit are small nutlets held together in a catkin-like aggregate of fruits called strobiles. Fruits can be collected in the spring in May to June just as they turn from green to brown. The fruits will separate from the catkin-like aggregate and be spread by wind. Collect seed before it is released and scattered. They can be stored dry for several years in air tight containers in the refrigerator.
Seed dormancy: River birch seeds are non-dormant if germinated under long days (light for >16 hours). In order to germinate in the dark, seeds need to be stratified for 60 days
Seed germination: Sow seeds on the surface of the substrate in a nursery container to produce a seedling or sow them in a plastic container in the classroom under long day light conditions to observe germination.