The key to successfully planting fir tree seeds is finding a good source of seeds. One option is to collect seeds in the fall from a female tree in your area. Planting a local tree's seeds will increase the likelihood that it will grow well on your property. Another option is to order seeds online where you may be able to find an interesting exotic cultivar. Whichever method you choose, be sure to collect or buy many more seeds than you think you will need. Even seeds found from a reliable source will not all be viable.
Test the fir tree seeds for viability by placing them in a cup of water for 24 hours. Discard any seeds that float. They are unlikely to germinate.
Dry the seeds.
Fill the 4-inch pot with compost. Lay four seeds on top of the compost, a half inch apart. Then cover the seeds with horticultural grit that is roughly twice the size of the seeds.
Water the compost so that it is moist and move the pot to a sunny windowsill. Continue to keep the compost moist until it is time to transplant.
Fill a 12-inch pot with potting soil.
Pick out the largest (or only) seedling one week after the seedlings emerge and transplant it into the 12-in pot. Water the soil so that it is moist.
Move the 12-inch pot to a sunny spot near a window. Continue to keep the soil moist.
Transplant the sapling in the spring outdoors when it reaches 1-year-old. Pick a spot that offers partial shade and has soil with a pH between 3.7 and 6.5.