To stratify indoors, mix the seed with a moistened, sterile, peat based growing medium in a container, wrap in a ventilated bag, and place it in a refrigerator for 12 to 20 weeks. In the spring plant seed in a sheltered spot outside to grow into seedlings.Click to see full answer. Likewise, people ask, how do you germinate Douglas fir seeds?Collect a cone from a Douglas-fir tree with desirable characteristics such as shape. Remove the wings from the seeds by gently rubbing the seeds in between your fingers. water to start the germination process. After soaking, place the seeds on a paper towel and allow them to dry for another 24 hrs.Beside above, how do you prepare tree seeds for planting? Cover the seeds with a fine layer of sand to a depth about the thickness of the seed. After planting the seeds, gently water them and keep them moist but not wet. Maintaining high moisture and relative humidity is critical to germinating seeds. You can increase the humidity by enclosing the seed tray in a plastic tent. In this manner, how do you grow a Douglas fir? Plant in pots no smaller than 6 inches deep, make sure that your potting soil is has good drainage so that it will hold moisture without getting soggy. Plant seeds about 2 inches deep, then cover with soil. Keep in partial shade for the first year; older seedlings will require full sunlight.How fast does a Douglas fir grow?A cultivated tree never achieves the same height or grandeur. In your yard, a Douglas fir will only grow 40 to 60 feet tall. Experts at Cal Poly estimate the growth rate of Douglas fir at 24 inches a year, but this also depends on its growing conditions.