It is not advisable for babies to add complementary foods later than six months. As we all know, mother's milk is the best food for babies, and exclusive breastfeeding is becoming more and more popular. But many mothers have fallen into another misunderstanding: they blindly feed their babies breast milk and ignore the necessary supplementary foods. It is understood that most mothers are concerned about when their babies can start adding complementary foods. 9-11 months old baby's complementary food recipes. After 9 months, babies generally have about 4 small teeth and can chew slightly harder foods. Digestion is also enhanced than before, and it is best to use soft rice or porridge as the main food as a supplement.