This guide is for volunteer leaders or county Extension personnel, and includes four lessons designed for youth in 3rd‐5th grades. Each lesson focuses on an aspect of seeds, plants, and/or gardening. Three additional experiments are included in the Digging Deeper section that youth can do independently or in a group or classroom setting. At the end of the guide, additional resources and an appendix are available. The National 4‐H Gardening Series, which includes 4 levels for grades 3rd‐12th and a Helper's Guide, is recommended if additional background information is needed. The National 4‐H Gardening Series includes projects and activities for youth that have an interest in continuing to learn more about plant science and gardening after completing their windowsill garden.