Information on critical phosphorus (P) concentration in tissue of Stenotaphrum secundatum (Walt) Kuntze cultivar ‘Floratam’ (St. Augustinegrass) and Zoysia japonica cultivar ‘Empire’ (Zoysiagrass) is limited. Knowledge of critical leaf tissue P concentrations for these turfgrass species can help to avoid unnecessary P fertilization and reduce the risks of negative consequences to the environment. A hydroponic study was established to determine the critical P concentration in leaf tissue of ‘Floratam’ St. Augustinegrass and ‘Empire’ zoysiagrass. Six levels of P (0, 90, 135, 203, 304, and 456 mg P m^-3) were used. Plant growth rate, P concentration in leaf tissue, visual ratings of turfgrass quality, percent green turf cover and chlorophyll index (CI) were evaluated biweekly for 140 days. Turfgrass visual quality rating increased with increasing P supply. Maximum zoysiagrass growth rate and percent green cover were reached at 1.67 g P kg^-1 and 1.35 g P kg ^-1, respectively. Maximum St. Augustinegrass growth rate and percent green cover were reached at 1.73 g P kg^-1 and 1.48 g P kg ^-1, respectively. Consequently, a P concentration in leaf tissue of 1.35 g P kg^-1 and 1.67 g P kg^-1 for zoysiagrass and 1.48 g P kg^-1 and 1.73 g P kg^-1 for St. Augustinegrass could be used as the threshold concentrations for maintenance of maximum green turf density and maximum growth and recovery rates, respectively. Phosphorus fertilization in low P retention soils can result in P leaching to ground water. Another study was conducted to evaluate the effect of P application rate on orthophosphate (P_i) leaching. St. Augustinegrass and zoysiagrass were grown in a “clean” sand with very low extractable P and negligible P soil storage capacity. Five rates of P were supplied (from 0 to 5 g m ^-2 year^-1). Phosphorus uptake, plant dry matter accumulation, and Mehlich I extractable P (M1-P) were determined biweekly for 140 days (May to September) during 2008 and 2009. Orthophosphate leaching rate and P _i concentration in leachate from zoysiagrass were greater than from St. Augustinegrass. Phosphorus uptake rate over time in St. Augustinegrass was greater than in zoysiagrass. The root system of St. Augustinegrass was more extensive and deeper than in zoysiagrass. Rate of P_i leaching was positively related to amount of rainfall plus irrigation received by the turf. Phosphorus fertilization over time increased M1-P, phosphorus saturation ratio (PSR) and reduced of the soil phosphorus storage capacity (SPSC). Greater volume-weighted P_i concentrations in leachates were measured in soils with greater M1-P and PSR values and lower SPSC values. Orthophosphate concentrations in compliance with the U.S. Environmental Protection Agency (USEPA) water quality criteria for Florida were measured in soils with a PSR as high as 0.6. Total estimated amount of P leached from fertilizer application was below 5% and 0.25% in zoysiagrass and St. Augustinegrass, respectively. The results of this research indicate that if P fertilization is required based on tissue analysis and the SPSC is positive, it would be environmentally safe to supply P at a maximum rate of 0.54 g P m^-2 per application (1.07 g P m^-2 per year) to St. Augustinegrass and 0.2 g P m ^-2 per application (0.8 g P m^-2 per year) to zoysiagrass.