Non-intrusive and accurate voltage, current and phase measurements of fundamental and harmonic radio-frequencies (rf) are compared with the temporal evolution plasma emission and scattered laser light from in situ formed particles in an argon-silane low-pressure rf discharge. The measured parameters show a corresponding behaviour during particle evolution. With increasing reactor temperature, not only is particle nucleation delayed in time but all subsequent phases of particle formation are slowed down as well. A close correspondence between the variations of the fourth harmonic of the current and the Si-H emission line is found. The results show that electrical parameters provide valuable clues to the particle growth starting from the nucleation phase, making them good candidates for process monitoring in industrial devices.