1. Agricultural landscapes feature marked seasonal changes in the quality and quantity of habitats and floral resources supporting pollinating insects. Seasonal dynamics can affect the structure of plant–pollinator interactions, yet the relative importance of both landscape elements with spatio-temporal dynamics and those elements that are more static in space and time remains largely unknown. Such an understanding is needed to identify resource-mediated modifications of plant–pollinator network structures and their functional and management implications. 2. To understand the spatio-temporal effects of landscape heterogeneity on the structure of plant–pollinator networks, we sampled plant–pollinator (Apiformes—except Apis mellifera; Syrphidae) communities over three seasonal periods in 12 landscapes in central Germany. The landscapes comprised spatial gradients in the proportion of semi-natural habitat cover and edge density. To assess temporal changes, we evaluated the cover of mass-flowering crops in bloom, floral diversity and honey bee density at each plant–pollinator sampling event. 3. Spatio-temporally dynamic characteristics, particularly the cover of mass-flowering crops, were more important than static characteristics in explaining variation in plant–pollinator network structure across the three seasonal periods. The richness of plants and pollinators was generally lower when the proportion of mass-flowering crops was high. Under such conditions, networks were more connected, with greater niche overlap among pollinators, and decreased network specialization (H2′). Richness was higher in landscapes with high edge density, with an increasing effect on network connectance up to a certain threshold. The proportion of semi-natural habitat cover and floral diversity had differential effects on the richness of plants and pollinators, with strong effects on the dietary niche overlap of the pollinators, potentially indicating a decrease in competition when semi-natural habitat cover and flower diversity are high. 4. Synthesis and application. To better support plant–pollinator communities in agricultural-dominated landscapes, we suggest incentivizing the planting of complementary floral resources and preserving or restoring semi-natural habitat areas. Especially in intensively used agroecosystems, the negative effects of mass-flowering crops can be mitigated by maintaining flower-rich edge habitats and relatively small field sizes, which help support plant and pollinator communities, avoid potential negative effects of exploitative competition, and ensure the sustainability of pollination services via increased functional redundancy.