As the world urbanizes and technologies such as LED grow lights bring down costs, indoor farming is becoming an increasingly important part of the food supply. Eventually, indoor farming techniques could help humans maintain a healthy diet in space. However, because of the completely closed systems in which indoor crops are grown, imbalances in soil nutrients, salinity, temperature, and other factors must be caught quickly to avoid losing a whole crop. In work published in a recent issue of Applications in Plant Sciences, Dr. Robert Ferl and colleagues at the University of Florida Space Plants Lab developed a light-based tool to assess plant health quickly, accurately, and inexpensively.