I developed theory and experiments to understand how complex life cycles of a host affect the dynamics of their heritable symbionts, important ecological and evolutionary agents. With symbiont persistence and prevalence being a function of their effects on host fitness and transmission efficiencies, accounting for host demographic “storage,” in the form of non-reproductive or dormant host life stages, leads to unexpected results. Symbiont loss from demographic storage affects persistence similarly to loss from a host reproductive stage. Loss from host dormancy, however, affect dynamics if symbiont passage through the dormant stage occurs at a high rate, which we observed with experiments. Demographic rescue and symbiont persistence was possible, and observed, whereby stage specific symbiont benefits compensate for symbiont loss. Empirically, accounting for host dormancy in the form of a plant seed bank facilitated symbiont persistence and prevalence. Our results emphasize the importance of accounting for realistic complexity in host-symbiont dynamics.