Here we report the effect of 23 years of experimental warming on plant traits across four different alpine subarctic plant communities. Changes in leaf width, leaf length and plant height of 22 vascular plant species were measured. Long-term warming significantly affected all plant traits. Overall, plant species were taller, with longer and wider leaves when compared with control plots, indicating an increase of biomass in warmed plots. 13 species having significant increases in at least one trait and three species having only negative responses. The response varied among species and plant community, in which species was sampled, indicating community-warming interactions. Thus, plant trait responses are both species- and community-specific. Importantly, here we show that there is likely to be great variation between plant species in their ability to maintain positive growth responses over the longer term, which might cause shifts in their relative competitive ability.