We report time-resolved (ps) studies of the dynamics of intersubband transitions in p-Si/SiGe multi-quantum well structures in the FIR regime, ?? < ??LO. utilizing the Dutch free electron laser, FELIX. The calculated scattering rates have been included in a rate equation model of the transient FIR intersubband absorption, and are in excellent agreement with our degenerate pump-probe spectroscopy measurements where after an initial rise time determined by the resolution of our measurement, we determine a decay time of ~10 ps. In strong contrast to similar measurements on p-GaAs quantum wells, this is found to be approximately constant in the temperature range from 4 to 100 K, in good agreement with the predictions of alloy scattering in the Si0.7Ge0.3 wells.