when is a good time to trim a white pine tree?
Answers:
late fall to early winter, as you want to give it time to set next years buds, never prune in the early spring. You can cut unwanted spring growth in summer to shape up the plant.Do not cut branches back to old wood with no growth on it, as you won't develope any buds and the branch will be considered 'dead'
Other answers:
I don't think it matters when you prune pine trees.
I don't think it matters when you prune pine trees.
If the branches are dead cut them out, white pines usually recover quickly. Trim the tree in the fall, after first frost for less sap drip. You should also be able to shape the tree at the same time for symmetry. Seal all cuts with a good tree wound sealant.
I would trim it in the spring and summer.
Prune in the late fall or winter and don't remove more than 1/3 of the total vegetation.