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Successive observations of the dynamics of populations of actinomycetes initiated by soil moistening at three levels of moisture content values (field capacity, wilting point, and maximum air-dry moisture), made it possible to reveal conditions and time intervals most favorable for isolating rare genera. The actinomycetes of the following seven genera were isolated from the samples of steppified desert soil: Streptomyces, Micromonospora, Saccharopolyspora, Actinomadura, Streptosporangium, Dactylosporangium, and Nocardia. The maximum population density of representatives of the Streptomyces, Micromonospora, and Streptosporangium genera was observed when soil was moistened to the maximum air-dry moisture; and the maximum population density of the representatives of the Saccharopolyspora, Nocardia, Actinomadura, and Dactylosporangium genera was observed under higher moisture content. Maximum population densities of different genera of actinomycetes fell on different succession stages, i.e., every genus of actinomycetes had its own place of maximal development in succession.