Non-perennial streams (NPS) are diverse and widespread in cool, wet temperate countries including England. Here and around the world, NPS are exposed to multiple anthropogenic pressures including enrichment by inorganic nutrients. Regulatory agencies therefore need to collect data enabling assessment of nutrient pressures in both wet and dry NPS channels. While aquatic plant communities are routinely used to monitor nutrient pressures, their species die back during dry phases, while terrestrial plants colonize. We therefore developed a method using dry-phase plant communities—comprising persisting aquatic taxa and colonizing terrestrial taxa—to assess nutrient pressures across England’s NPS, including sites spanning alkalinity, altitude and nutrient-pressure gradients. We investigated the responses of metrics representing community richness, cover, diversity and nutrient tolerance to predictors based on nitrogen and phosphorus concentrations, and their interactions with alkalinity, altitude and shade. Our aim was to identify metrics with consistent, strong, non-interacting responses to nutrient-based predictors. Cover-weighted nutrient-tolerance metrics were particularly responsive to nutrient concentrations, although alkalinity, altitude and shade affected many relationships. We recommend considering a cover-weighted nutrient-tolerance score alongside a metric of taxonomic richness (as a measure of confidence) in dry-phase nutrient-pressure assessments. Our results also demonstrate the considerable contribution that terrestrial plants make to the total biodiversity of NPS. As these dynamic ecosystems increase in extent due to global change, our methods could enhance programmes that support biomonitoring of their ecological health.