Consider the following
d = data.frame(y=rnorm(120), x=rep(c(\"bar\", \"long category name\", \"foo\"), each=40)) ggplot(d,aes(x=x,y=y)) +
Alternatively, flip the axis, your customers will thank you and have less neck pain (plus, I find most boxplots easier to interpret with this orientation):
ggplot(d, aes(x = x, y = y)) + geom_boxplot() + coord_flip()