This species is found on volcanic rock in xerophyllous scrub. Mammillaria duwei is known from only one location, has a small population size, and there is a continuing decline due to overcollection and development. The southernmost of the two known subpopulations of this species has declined as a result of collecting over the past 15 years. Currently the total population is estimated at approximately 500 individuals. The plant you receive might not be flowering.