Leaf area measurements are commonly obtained by destructive and laborious practice. This paper shows how stereo and Time-of-Flight (ToF) images can be combined for non-destructive automatic leaf area measurements. We focus on some challenging plant images captured in a greenhouse environment, and show that even the state-of-the-art stereo methods produce unsatisfactory results. By transforming depth information in a ToF image to a localised search range for dense stereo, a global optimisation strategy is adopted for producing smooth results that preserve discontinuity. We also use edges of colour and disparity images for automatic leaf detection and develop a smoothing method necessary for accurately estimating surface area. In addition to show that combining stereo and ToF images gives superior qualitative and quantitative results, 149 automatic measurements on leaf area using our system in a validation trial have a correlation score of 0.97 with true values and a RMSE value of 10.97 cm².