A few weeks ago, I noticed that the Phoenix roebelenii (Pygmy date palm) in my living room seemed higher in its pot, the soil actually starting to spill over the top of the planter. I had planted it with about an inch of space between the top of the soil and the top of the pot and figured that it was a little too happy and that it had outgrown its pot already–but after only one year? I took it outside to repot it and upon pulling it free of its terra cotta planter, discovered that it had devoloped a perfect ring of roots on the bottom that sure enough had slowly pushed the plant up.