See blog on adding manual legend as well as this RStudio community post Adding manual legend to ggplot2 to add in custom legends when aes() aren't called. Personal preference the first link is less hacky than the second. As legend title and legend text should be adjusted using names and labels arguments in scale_colour_manual(). For your situation you'll have to move colour = "red" into aes(). Then manual change both the colour and label with something like scale_colour_manual()