Semipolar (1 -101) GaN layers were grown by metal-organic chemical vapor deposition on patterned (001) Si substrates. The effects of reactor pressure and substrate temperature on optical properties of (1 -101) GaN were studied by steadystate and time-resolved photoluminescence. The optical measurements revealed that the optical quality of (1 -101)- oriented GaN is comparable to that of c-plane GaN film grown on sapphire. Slow decay time constants, representative of the radiative recombination, for semipolar (1-101)GaN grown at 200 Torr are found to be very long (~1.8 ns), comparable to those for the state-of-art c-plane GaN templates grown using in situ epitaxial lateral overgrowth through silicon nitride nano-network. Defect distribution in the GaN stripes was studied by spatially resolved cathodeluminescence measurements. The c +-wing regions of the GaN stripes were found to be dominated by a (D 0,X) emission. Only a thin slice of emission around 3.42 eV related to basal stacking faults was revealed in c --wing regions.