Janie 'hates' her grandmother because she feels that Nanny is limiting her potential. She doesn't exactly realize this at the beginning of the novel, but Janie knows that she doesn't like the way her grandmother is always making decisions for her. Nanny chooses what she thinks is best for Janie, rather than allowing Janie that opportunity herself. Nanny wants Janie to marry into money so that she doesn't have to work and she can be comfortable. By the end of the novel Janie realizes why she despises her grandmother's limiting demands when she finds real love and it has nothing to do with money, wealth and prestige. Janie loves her grandmother because she is trying to protect her, but she hates her when she feels that she has no choice in her own life. Nanny is trying to protect Janie from having a hard life, but that isn’t necessarily what Janie wants for herself.