The problem of growth dynamics for crystals of binary solid solutions, obtained by the constitutional supercooling of the melt with a silicon feeding rod, has been solved within the Pfann approximation. The dependences of the change in the axial growth rate of Ge1−xSix crystals (0 ≤ x ≤ 0.3) are calculated. It is shown that the Ge1−xSix crystallization rate significantly changes during growth. The results make it possible to determine the optimal conditions and technological parameters for growing Ge1−xSix single crystals (0 ≤ x ≤ 0.3) with a specified concentration gradient along the crystallization axis.