Display the x-axis on ggplot as month only in R

For me, what worked was

library(scales)

+ scale_x_date(date_labels = "%b-%d-%Y")

More info here

As your x values are date you can use scale_x_date() to change format of labels. Library scales is needed to get better formatting of breaks and labels.

library(scales)
+scale_x_datetime(labels = date_format("%b"))