When Sam got killed and went to the hospital when he became ghost, he sanks on the hospital chair, and when he's sinking, he touches the plant (which is on his left) with his arms, so clearly. This scene happens just before he meets another ghost(old man) who says he's waiting for his wife.
You do mean that it's because it takes him a while to learn how to "touch" things right? Well in that case how did he "sank" into that chair?? *without falling through it* ;)