Disclosed herein are exemplary embodiments of various grass-growing devices. In one nonlimiting embodiment, for example, a device for growing grass in a container that provides water to a household pet is disclosed. The device includes a basket that is configured for insertion into the container. The basket comprises one or more apertures that allow for fluid movement through the basket. The device further includes a seed-holding unit. The seed-holding unit of this embodiment comprises a housing in which one or more grass seeds can be placed.