My spruce trees produce hundreds of seeds, but when I plant them very few germinate and the ones that do don't overwinter. I was sowing them in fall to overwinter and sprout in spring in acidic, humusy soil in full sun. How should I be doing this?
According to the National Christmas Tree Association:
According to Floridata:
So I would hold the seed over winter (perhaps in the fridge -- I think most conifers want a cold period to break dormancy), and plant in the spring in acidic, well-drained soil.
Lastly, I know people who grow Christmas trees, and they expect significant losses (in related species, not necessarily Norway Spruce) when they plant from seedlings, so I wouldn't expect all of the seeds you plant to survive. A good strategy might be to sow 10x (or even 100x) what you want, and then thin to the strongest survivors after a couple of years.