Seedlings of Ferocactus wislizeni and Mammillaria grahamii, 2 common cactus species in the northern Sonoran Desert, emerged under protective cages that had been left in place for 6 years after an initial sowing of numerous Carnegiea gigantea and F. wislizeni seeds. Because no seeds were sown in the interim, Mammillaria and Ferocactus seedlings must have emerged from persistent seed banks. Mammillaria seeds evidently survived in or on the soil as long as 6 years, forming a long-term persistent seed bank, and Ferocactus seeds apparently survived up to 3 years, forming a short-term persistent seed bank. No Carnegiea seedlings emerged, confirming that this species has a transient seed bank This is the first evidence for a between-year seed bank in M. grahamii and the first confirmation of a between-year seed bank in F. wislizeni.