Is Korin the only one able to grow Senzu Beans?
An entry for Korin in the Dragon Ball wikia states that, Korin is the only one who grows the Senzu Beans which... and that 
Korin Tower is the only place in the world they are grown...

Apart from that, the entry for Senzu Beans depicts Korin as the inventor of the Senzu Beans.

Based on that, it can be presumed that one of these are true:


Korin invented the Senzu Beans and thus he is the only one who can cultivate them.
The Senzu Beans need a very particular habitat to grow and Korin Tower happens to be the only place matches its needs. 


Do note however, that the wikia does not mention if there was any explicit reference to this matter in the Manga.