Augmented Reality (AR) is rapidly gaining popularity, enhancing human perception of the real world by augmenting digital experiences. Existing tools for authoring AR scenes are either template based or require domain knowledge from experts, and are therefore restrictive. ARComposer is a novel interface that enables easy authoring of AR experiences from free-form text describing the scene. Our proposed interface allows creators to compose varied scenes comprising of multiple objects with diverse relationships to each other as well as human models with animations, starting merely with a textual description. A qualitative evaluation shows that ARComposer provides a good flow experience to its users. Furthermore, a crowd-sourced experiment evaluating various aspects of the rendered AR scenes indicates the viability of the proposed approach.