Why is the ninth month called September?
"plant not valued for use or beauty," Old English weod, uueod "grass, herb, weed," from Proto-Germanic *weud- (cf. Old Saxon wiod, East Frisian wiud), of unknown origin. Meaning "tobacco" is from c.1600; that of "marijuana" is from 1920s.
"to clear the ground of weeds," late Old English weodian, from the source of weed (n.). Related: Weeded; weeding.