Growth model projections were compared with actual harvest data of 5-year-old short rotation intensively cultured Populus. Several factors were identified that influence the accuracy of growth and yield predictions, including: (i) plot design and establishment techniques; (ii) cultural and environmental factors; (iii) measurement procedures, and (iv) model limitations. Knowledge of these factors helped explain observed differences between the projections and the actual harvest. Such knowledge also provided useful feedback information in model recalibration as well as a better understanding of the experimental, sampling, and operational errors.