Seriously ....... Ganja in that circle is "don't ask, don't tell". Ganja is a part of Jamaican culture but many visitors don't understand one big thing. Do they really believe that the whole country is stoned/stupid all day?
When was the last time you saw someone at your hotel stoned? Yes, up in the hills the poorer class of young men smoke all day . The females are too busy making a living to smoke herb during the day.
You're on vacation so smoking and drinking all day is cool. But never think that what goes on on the 7 mile beach and cliffs is Jamaican standard.
So to answer the OP......... you won't have any problem finding herb in Negril. Just ask your hotel staff about where to smoke.