Experiments were conducced to test the effects of physical factors on arbuscular mycorrhiza inoculum production and storage. The production of a soil-based inoculant in 0.7 m³ containers has proved feasible, and propagule numbers were increased by raising the soil temperature. Inoculant production in a greenhouse using 20 L containers was not affected by daily irrigation rates, but submitting leek plants to a slight drought stress improved sporulation and increased the number of mycorrhizal fungal propagules. The evaluation of propagule number of a soil-pouzzolan based inoculant and of its different components indicated that extra-radical hyphae of Glomus mosseae are an important contribution to the infection potential. Manipulation of inoculants should, therefore, consider this and be reduced. A storage experiment showed that high temperatures severely affect infection potential of inoculants, and that soil-based inoculants may conserve their infection potential longer than commercial products based on expanded clay. The results show that physical factors, such as soil water content and temperature, should be carefully considered in production and storage of arbuscular mycorrhiza inoculants.