Answer: Pinus torreyana, the Torrey Pine, is a fast growing tree and will reach 40-60' at maturity with a 30' width. Spaced 10' apart they will begin to crowd one another in a few years. If you're looking for a dense screen or windbreak, the spacing will accomplish that. I'd tend to space them about 20' apart - they'll eventually grow together, but until then, you'll be able to appreciate their attractive branching habit. Torrey Pine resents being pruned, and pruned branches will die back to the trunk, so initial spacing really is important. Give them room and you won't have to prune. They are not particularly insect or disease prone, but plants under stress are sometimes attacked by pests.
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