Changing global climate patterns may have a significant impact on plant phenology. In the northern hemisphere plants have responded to warmer temperatures by flowering earlier and sustaining longer periods of growth. Changes in atmospheric N deposition and precipitation may also affect plant phenology. We tested the effects of increased winter precipitation, summer temperature and nitrogen (N) on plant phenology in an alpine moist-meadow community at the Niwot Ridge LTER site. Treatment effects were simulated using snowfences, open-top warming chambers and N fertilizer in 1 m2 plots. Experimental plots included a total of 20 different forb and 8 different graminoid species. Phenology was measured by visiting plots every 2 to 5 days during two growing seasons and recording flower presence. For dominant species the number of individual flowers present was measured in all plots following peak flowering. Phenological response to treatments varied among species and functional types. Three dominant forb species (Geum rossii, Bistorta bistortoides, and Caltha leptosepala) responded to warmer summer temperatures by flowering 1.67 days earlier than in control plots (P = 0.0308). An interaction effect between snow and N affected first flowering date of G. rossii and B. bistortoides in which for both species snow augmentation and N addition alone delayed flowering by almost two days, but snow and N together resulted in no difference in flowering phenology compared with untreated plots (P = 0.0125 and 0.0470 respectively). Across eight graminoid species, plants flowered almost 3 days earlier where N was added (P = 0.0264). Additionally, we found an average of two fewer flowers of B. bistortoides in plots where summer temperature was increased (P = 0.0375). Our results indicate that changing global climate patterns may have a significant impact on plant phenology, and specifically highlight how increased N due to atmospheric deposition my interact with warming temperatures to affect phenology. Alpine plants are limited by a short growing season and even small changes in the timing of phenological events may translate into large changes in community composition. Longer term precipitation, temperature and N manipulations will be required to determine clear and predictable patterns of modified alpine plant phenology in response to climate changes.