Warming and higher nitrogen loading induced by increasing precipitation are expected scenarios in north temperate regions as consequence of global climate change, with potential effects on the functional traits of submerged macrophytes and periphyton. Using an experimental heating facility we investigated the responses of three-week growth of two submerged macrophytes (Potamogeton crispus Linn. and Elodea canadensis Michx.), and periphyton on these plants and their artificial mimics. Analysis was based on IPCC climate scenarios A2 (ca. + 3 degrees C) and A2 + 50% (called A3 in our study) relative to ambient conditions, across warming in spring and early summer (summer showed higher nitrogen loading). Some functional traits of plants showed species-specific responses to warming: A3 promoted the growth of E. canadensis in both seasons, while for P. crispus warming reduced the leaf number in spring but enhanced the turion production in early summer. Periphyton biomass was lower in A3 in early summer, but not in spring. Our results further show that the growth of E. canadensis and the asexual reproduction of P. crispus might increase in a warmer future. Moreover, we found a complex response of periphyton to the temperature increase and substrate type, varying with season and nutrient state.