Identifying methods to improve crop productivity is vital considering the devastating consequences of climate change (e.g., frequent droughts). Stomatal conductance influences photosynthesis and water use efficiency, which are two important indicators of crop yield. Here, Faralli et al. discuss advances in understanding how stomatal traits vary and how these may be manipulated to improve stomatal conductance. Genetic manipulation of stomatal conductance is discussed with the view to stabilise yield and water use in crop species. Natural variation of stomatal conductance exists within populations and is identified as an underutilised non-GM target for crop breeding programs (Summary by Alex Bowles) Curr. Opin. Plant Biol. 10.1016/j.pbi.2019.01.003.