Although colours, when used as an adjective with a noun, do agree with the latter in gender and number this is not the case when you are talking about the colour itself. It then is invariable.
You would say-
"la maison grise/verte/bleue/blanche"
" la maison peinte en gris/bleu/vert/blanc" ( painted in the colour grey/blue/ etc.)
But well spotted!
Sign in to submit your answer
Don't have an account yet? Join today
Test your French to the CEFR standard