Dewatering of saturated soils, sediments, and similar substrates is an emerging issue that requires a low cost solution. Plants have the ability to remove water from the substrate in which they grow through transpiration and could be used to aid in moisture removal. However, the need exists for a rapid screening tool to identify plant species with high transpiration rates that can grow in high water content substrates. This study examines the relationship between plant silica content and plant transpiration rate. A variety of plant species and types were grown in two soils to understand the relationship between silica and transpiration. Using an Infrared Gas Analyzer (IRGA) to quantify transpiration rate and acid-insoluble ash to quantify silica, a statistically significant relationship (p < 0.01) between plant silica content and plant transpiration rate was determined. Plant type (wetland, grass, or forb) also was a significant (p < 0.01) indicator of plant transpiration rate. These tools combined with knowledge of plant growth characteristics can be used in identifying plant species well-suited for particular dewatering applications.