Calcium silicate has been used to supply silicon (Si) as a plant nutrient for enhancing crop production and the suppression of turf diseases. Research was initiated to determine the effect of calcium silicate on turf quality and its residual activity in providing plant available Si in two turfgrass systems. During 2005 and 2006, calcium silicate (Excellerator, 12% Si) was applied as a topdressing at eight rates ranging from 0 to 342 kg m^-2 to a FloraDwarf (Cynodon dactylon x C. transvaalensis Burtt Davy) green in the spring and to the same plots overseeded with rough bluegrass (Poa trivialis cv. Wintergreen) in the fall. At initiation of the study, dolomitic limestone was applied to equilibrate calcium across all treatments based on the highest rate of calcium silicate. Every 28 days, treatments were rated for turf quality and then harvested to determine Si accumulation. One month after applying calcium silicate in 2005, percent Si in the leaf tissue of FloraDwarf generally increased linearly with increasing rates. This response continued through the months of May, June, July, August and October with a 9.2%, 20.9%, 40.4%, 22.2% and 21.1% increase in Si concentration in the leaf tissue between the control and 342 kg m^-2, respectively. Although the rate response remained, there was an overall drop in average percent Si in leaf tissue across the treatments beginning three months after the first application. Similar responses were noted with the overseeded grass with a 46.4%, 84.9%, 69.4%, 111% and 58.2% increase in Si concentration in the leaf tissue between the control and 342 kg m^-2, respectively. In contrast to the bermudagrass, over the five month period following application, the residual activity of Si in P. trivialis remained high, suggesting that P. trivialis is a better Si accumulator in comparison to FloraDwarf bermudagrass.