i am white with dreadlocks and i try to follow the way of jah i havent seen any discrimination to my dreads because i am white..as i belive that they see that im not just doing it to smoke ganja as im in it it for the spirtual not the material..all of the jamaican rasta's i have met have been genarlly nice and accepting of me as i ussaly like to talk with them about rastafarianism..as for the reason for growing dreadlocks in the rasta religon rastas let their hair grow natually into dreadlocks, in the image of the lion of Judah and they are not to shave there head or shave the corner of there beard nor make any cuttings in the flesh "All the days of the vow of his separation there shall no razor come upon his head: until the days be fulfilled, in the which he separateth himself unto the LORD, he shall be holy, and shall let the locks of the hair of his head grow."In 1954, the Pinnacle commune was destroyed by Jamaican authorities. By the 1950s, Rastafari's message of racial pride and unity had unnerved the ruling class of Jamaica, and confrontations between the poor black Rastas and middle-class police were common. Many Rastas were beaten, and some killed. Others were humiliated by having their sacred dreadlocks cut off.

and as far as "marijuana" Ganja is considered the "wisdom weed" by Rastafarians, as its use helps one to gain wisdom. Rastafarians use it as a part of a religious rite and as a means of getting closer to their inner spiritual self, Jah and Creation.and as far as the race issue i would like to quote H.I.M. Haile I Selassie
"InI (We) must become members of a New Race, overcoming petty prejudice, owing InI (Our) Ultimate Allegiance, not to Nations, but to InI (Our) fellow Man within the Human CommUNITY".....
H.I.M. Haile I Selassie I....JAH RASTAFARI !