This is a short middle-grade novel which I read as a library book in the late ’80s or early ’90s, but may be older. A group of female friends (I think three) fix up and decorate an old house for the older brother of the narrator. He is just getting out of the hospital, either for mental illness or a suicide attempt, and they want to give him a nice place to feel at peace. They paint the walls purple. The brother may be named Joe. When he sees the house (or maybe it’s just a room?), he seems underwhelmed and doesn’t say anything. The main character is very disappointed. Later she goes back to the house and discovers the plants have been watered and the brother has been using it after all. But there’s a sad tinge; maybe the brother has gone back to the hospital or disappeared? One of the girls is Japanese-American and gets romantically involved with one of the older boys who is helping, and the main character is jealous. The illustrations are kind of trippy, showing the girls with very long hair. The cover or illustrations are purple, or possibly the word purple is in the title.