<p>We conducted a four-year warming × moisture × N-deposition field-experiment (AlpGrass) with 216 turf monoliths from six different subalpine pastures (sites of origin). At a common location, the monoliths were replanted at six climate scenario sites (CS) along an altitudinal gradient from 2360 to 1680 m a.s.l., representing an April–October temperature change of −1.4 °C to +3.0 °C, compared to CS<sub>reference</sub> with no temperature change and with climate conditions comparable to the sites of origin. We further applied an irrigation treatment (+12–21 % of ambient precipitation) and an N-deposition treatment (+3 kg and +15 kg N ha<sup>−1</sup> a<sup>−1</sup>), the latter simulating a fertilizing air pollution effect.</p> <p>Moderate warming led to increased productivity. Across the four-year experimental period, the mean annual yield peaked at intermediate CSs (+43 % at +0.7 °C and +44 % at +1.8 °C), coinciding with c. 50 % of days with dry soil during the growing season (growing-season-days with soil moisture < 40 %). The yield increase was smaller at the lowest, warmest CS (+3.0 °C), but was still 12 % larger than at CS<sub>reference</sub>. Days with dry soil explained the average yield-differences among CSs well. Irrigation had a significant effect on yield (+16–19 %) in dry years, whereas atmospheric N-deposition did not result in a significant yield response. We conclude that productivity of semi-natural, highly diverse subalpine grassland will increase in the near future. Despite increasingly limiting soil water content, plant growth will respond positively to up to +1.8 °C warming during the growing period, corresponding to +1.3 °C annual mean warming.</p>