As I mentioned on my posting about this species, my experience has been that a very wide
pot is quite helpful. Two years ago, I had one of my largest rajahs in a 20 cm pot, in which
it had been growing for three years. I decided to remove it from the pot to ascertain the
extent to which its roots had permeated the compost. To my surprise, it was completely
rootbound, with the roots permeating the top three inches of the compost almost exclusively.
At that point, I put it in a shallow pot, 45 cm in diameter. Within a few months, it increased in
size and produced new basal growth.
Due to the rather extraordinary size of the leaves and pitchers of this species, it seems
reasonable to infer that it requires an extensive root system to satisfy its needs. Even
some of the smaller specimens in my care have developed very robust root systems
rather disproportionate to their size....