It has been reported by some UK outlets that Blues boss Antonio Conte is interested in bringing the Germany international to Stamford Bridge, with a bid of around £20 million thought to be sufficient, to provide Marcos Alonso with competition at left-back.
Goal reported on Wednesday, however, that Chelsea's interest in Hector has cooled.
But while Koln do not want to lose the defender, Stoger admits that the 26-year-old's future is in his own hands.
"I would not say that any player of any club in the world is not for sale, but we have extended Jonas' contract," Stoger is quoted by the Express. "And I think the player is clear - he knows what he wants. If there is any club Jonas is interested in, then we would talk to them.
"But Jonas didn’t say that he wants to leave the club and go to Chelsea so it doesn’t matter.
“If someone wants to leave the club then we have to talk about it, but not before."
Alonso has thrived in Conte's 3-4-3 formation, operating in the left wing-back role, and his introduction has coincided with Chelsea's stunning run of form.
Hector, who has strongly linked with a move to Liverpool last summer, has played every minute of Koln's Bundesliga campaign so far this term.