The Douglas fir (Pseudotsuga menziesii) is one of the most important timber trees in the United States, according to the University of Nebraska. It is also widely planted as an ornamental landscape tree and as a windbreak or natural privacy screen. Douglas fir trees reproduce from seeds developed and then shed from their pine cones. Propagating the seeds requires that conditions mimicking their natural growing habitat be met -- or improved upon -- in order for the seeds to germinate and the seedlings to grow and mature into trees. Patience is also required as mature Douglas firs' seeded cones are produced at irregular intervals, roughly every 7 years. The trees begin producing seeds only when they reach 20 years or older.
Harvest fresh seed from mature trees 20 years of age or older that come from mature cones that have fallen to the ground in the later fall, winter and spring. The seeds are small, lightweight and easily airborne with roughly 50 seeds produced by each bearing cone.
Plant the seeds immediately after harvesting, as they are genetically programmed to germinate in the spring. Plant the seeds in loose and well tilled, nutrient-rich moist soil either in nursery pots or in the ground soil. Nestle the seeds into the surface of the soil no deeper than 1/4 inch. Sprinkle the seed and soil gently with water to settle the seed in place but not so much water that you displace the seed or surrounding soil.
Select a planting or growing location where temperatures remain above freezing year round. Ensure that the site provides light shade for the first year of growth and full sun to very lightly filtered sunlight in the years thereafter.
Maintain evenly moist soil at all times around the trees and young seedlings. Feel the soil surface and a few inches down once a week and water as necessary to maintain the evenly moist soil. If you allow the seedlings to dry out they will go dormant, slowing their development and growth even further if they don't expire.
Pull out any and all weeds near the seedlings at the moment you see them. Weeds shade out the seedling and draw moisture away so they must be eradicated or the seedling will not survive or grow well.
Allow five years for your sapling to start to look like a classic tree. It will experience a significant growth spurt that will continue until the tree is 20 to 30 years old. Expect a lifespan of as much as 200 years for each tree, under good conditions.