Seashore Paspalum (Paspalum vaginatum) has yielded inconsistent overseed performance at mowing heights above 10mm which have included uneven stand, poor density, and  late spring transition. Thirty-two treatments were implemented on “Sea Isle I” which was comprised of select combinations of preparatory mowing heights, light vertical mowing, with and without and applications of glufosinate aluminum, pelarogonic acid, diquat, or trichlopyr. Preparatory mowing heights on turf regularly mowed at 15 mm included the fixed treatments of (M1) elevated to 31 mm; (M2) elevated to 31 mm inch, mowed to 18 mm then to 15 mm, then to 9 mm, (M3) mow to 18 mm then to 15mm before overseeding. The turfgrass was overseeded at the rate of 700 kg/hectare and evaluated for overseed cover and turfgrass quality from November 2009 to August 2010. Percent plot overseed ranged from 16% to 68% two weeks after overseeding. Treatments which produced high levels of emergence and fully acceptable turfgrass quality included (M2), diquat, and vertical mowing, (M2), trichlopyr and vertical mowing, and M1, glufosinate aluminum and vertical mowing. Without vertical mowing or herbicide, (M1) mowed turf produced quality averages of 6.0 or greater on only 6 of ten evaluation dates. Without the use of any herbicides, vertical mowing at the 9 mm mow height produced better overseed results than at 15 mm. Without vertical mowing or herbicides, mowing height preparatory treatments had no effect, which produced unacceptable turf quality at some point throughout the season. These results show the beneficial effect of specific mechanical canopy manipulations with the use of select herbicides for improving the overseed performance of Seashore paspalum in a semi-arid environment.