I recently acquired a young douglas-fir and was reading up on them. It doesn’t seem like it ought to be treated the same as a pine, and I was leaning towards putting it on a schedule similar to my yew (taxus baccata), which would involve removing the second-year needles soon. In the yew this encourages back budding. Does anyone know if the douglas-fir is like a pine in that removing these needles might discourage back budding? Otherwise I’ll do half removed and half left on and report back.
Sounds like a good approach to experiment - I don’t have much experience with them so will be curious what you can learn.
I do not remove needles on my firs unless they have turned brown. I have found they back bud readily when healthy. Working mostly with sub alpine fir though.