Gardeners can grow a cedar tree from seed by collecting the small cedar cones, which resemble the more familiar pine cone. All types of cedar trees can be propagated from seed. A type of evergreen tree, the cedar emits a fragrant smell and grows into quite a large shade tree. Cedar trees require a period of cold in order to germinate, which is easily accomplished by planting the seeds outside before winter sets in.
Gather the cones from a cedar tree in late fall.
Prepare a lye and water solution in a lidded bucket, using 1 tsp. of lye per gallon of water. Place the cedar cones in the lye-water solution, and let them soak for two days. Check on the cones; if they feel sticky, prepare a fresh lye-water solution and soak them for two more days.
Wash the cones and allow them to dry at room temperature, which should take a couple of days. Run the cones across a mesh screen. The seeds will separate out from the pulp. Save the seeds, and discard the pulp.
Fill a sealable plastic bag with moistened sand. Place the cedar tree seeds inside the bag. Leave the bag in your refrigerator for at least 30 days, or up to 120 days. At the end of this period, the seeds are ready for planting.
Prepare a site for planting the cedar seeds. Turn over the soil with a shovel. Add a 1- to 2-inch layer of peat moss to the top of the soil, and work it in to increase soil acidity. Cedar trees prefer an acidic soil. Create a long furrow that's 1/2 inch deep. Leave 6 to 8 inches between furrows if you plan to create multiple rows.
Lay your seeds in the furrow, sowing no more than 50 seeds per foot. You can sow far fewer seeds per foot. Cover over the seeds with peat moss until it is level with the ground.
Moisten the peat moss with water until it is moist but not wet. Keep the soil moist until the seeds germinate, typically within 30 days.
Do not water the seedlings once they have germinated unless the soil feels dry 2 to 3 inches below the surface. Then apply water to wet the soil.
Thin the seedlings out to one seedling per inch. Allow the seedlings to grow in the furrow for two to three years, or until they are 6 to 12 inches tall. Then transplant the seedlings to a new site where they have room to mature.