Nanostructures based on III-N materials are promising candidates for ultraviolet and visible light emitting devices. In particular, ternary InGaN nanowires (NWs) grown on semiconductor wafers perfectly fit to optoelectronic applications. In this paper, we will show that InGaN/Si NWs system is quite sensitive to the growth conditions and even a small change in the growth temperature leads to a significant change in morphological properties of the NWs and also shifts the photoluminescence spectra from blue to red regions with In content in the NWs increase. We will also demonstrate that, under specific growth temperatures, InGaN NWs may be grown in a form of core-shell structure where indium composition in the core is much higher than In content in the core one.