In a permanent trial on forest reclamation, we studied the growth characteristics of planted red oak stands from I to III age classes with the participation of gray alder as ameliorative species. The changes in mensuration variables and the mutual influence of the tree species have been studied in pure and mixed (with grey alder) planted red oak stands during the entire period of their growth. It was found that, over the 28 years, the intensity of growth has increased both in pure oak stands and in mixed ones. From 12 to 28 years old, oak site class grew from class V to class I in a pure oak stand and from class III to class Ia in a mixed one. For each variant of the trial and each breed, the coefficients for the equations for the course of growth by mensuration variables of a stand have been determined. The age for the removal of gray alder from the stand due to its drying out and loss of ameliorative function has been defined. The introduction of gray alder into the red oak plantations makes it possible to significantly improve their growth and to reduce the stand development phases, namely, to shorten the period for the planted stands to become closing, as well as promotes more rapid formation of the forest environment.