Palm trees are unique in that their roots don't grow straight down; they grow horizontally. Typically, palm tree roots go down between 12 and 36 inches deep. The roots grow far and wide from the base of the palm tree to absorb as much water and soil nutrients as possible. In addition, the horizontal roots are also very strong—keeping palm trees stable and helping them sway during storms.

No, you cannot plant a tree above a gas line. Tree roots grow and spread over time and can sometimes dent, crack, or penetrate a gas line. Those same roots may also cause accessibility problems for maintenance or repairs. You can generally plant vegetation with non-invasive root systems, low-growing vegetation, and flower beds near gas lines. 

Unfortunately, if you cut the top off a palm tree, it will die. Instead of budding or branching out, the top begins to slowly rot. That's why having a professional tree trimming at least twice a year is a good idea. If you don’t have experience with trimming your palm tree, you might accidentally cut the top off, leaving a dead and rotting tree in your wake.

Pruning trees during the summer can be a bad idea because the new growth will take place during the hottest months of the year, which can stress your tree out. Similarly, pruning during the early fall can be a bad idea, too, because you’d be stimulating new growth when most trees are aiming to go dormant. 

Pruning recommendations will vary by the type of tree, but generally, waiting until winter to prune your trees is a good idea.