The effect of planting date on Kentucky bluegrass (Poa pratensis) sod root growth was examined.� Kentucky bluegrass sod was established in spring, summer, and autumn in 2006 on a sandy loam soil located at the Turfgrass and Landscape Research Facility in Urbana, Illinois. �At 2 week intervals for a total of 10 weeks after establishment (WAE), cores were collected to a depth of 15 cm and analyzed using the WinRhizo System.� The WinRhizo System was used to analyze root architecture including total root length (TRL) and surface area (SA).� Each architectural parameter was categorized into diameter classes, 0 to 0.1, 0.1 to 0.2, 0.2 to 0.3, and >0.3 mm) and depth classes, 0 to 7.5 cm and 7.6 cm to 15 cm.� At the end of architectural analyses, roots were dried and biomasses recorded. �Pre-harvest sod cores were collected and analyzed in order to serve as seasonal controls.� Sod established in spring and autumn followed similar growth patterns and reached pre-harvest levels in terms of TRL and SA within 4 to 5 WAE.� However, root biomass of spring and autumn established sod was up to 50 % less than pre-harvest sod roots. �Pre-harvest sod had a greater proportion of roots within the larger root diameters classes compared to spring and autumn established sod.� Sod established in summer had slower root growth and did not attain TRL or SA of controls within 10 weeks.� Findings show spring and autumn provide optimal environmental conditions to enhance sod root growth compared to summer conditions.� However, measurement of sod root growth using biomass does not accurately indicate important root parameters such as TRL and SA.