Optimism surrounding adoption of switchgrass and other biomass crops is tempered by concerns such as the possibility of introducing transgenic or highly selected genetic material to native populations.  Pollen dispersal is one mechanism for such gene flow, and in order to effectively assess the potential for pollen-mediated gene flow it is necessary to know conditions required for switchgrass pollen release.  In support of such evaluations we have measured seasonal and daily trends of switchgrass pollen release via the use of passive deposition traps and volumetric air samplers in the summers of 2013 and 2014.  Measurements were conducted near switchgrass (Panicum virgatum L. ‘Cave-In-Rock’) plots at Iowa State University South Woodruff Farm near Ames, IA.  Results show the pollination periods in each year were similar. The period 17 August through 25 August accounted for approximately 75% to 80% of the total pollen collected in both 2013 and 2014. Diurnal trends of pollen release were also quite similar; the peak hour for both seasons was 2:00 pm local time. Daily average pollen concentration and temperature were not well correlated in 2013 but were highly correlated in 2014. For 2013, regression analysis of daily average pollen concentration resulted in a non-significant R² value of 0.073 (p=0.08) for daily high temperature and R² of 0.006 (p=0.615) for daily low temperature. Conversely, regression analyses of 2014 daily average pollen concentration and temperature showed significant R² values of 0.499 (p=0.001) for daily high temperature and 0.385 (p=0.001) for daily low temperature. There was no correlation between hourly pollen concentration and hourly temperature. These results provide a basis for establishing the trajectory and deposition of switchgrass pollen so that unintended gene flow can be monitored.