Measures to combat desiccation of Dutch nature reserves often lead to the establishment of buffer areas around them, in which soils become moisture, and agricultural yields decrease. Cultivation of the flooding-tolerant energy crop willow may be an alternative in such areas. In this study, the performance of willow production is compared to that of grass for roughage. The effect of high groundwater tables on yields of both crops is estimated using the agro-hydrological model SWAP. Financial consequences are evaluated by calculating the biomass price that, for a farmer, makes willow equally competitive as grass. At groundwater table class (Gt) II, common in buffer areas, willow physical yield is ca. 15% lower than its optimum, but grass yield decreases by ca. 25%, making willow more competitive. This results in a 20% lower break-even willow price on Gt II than in a drier, optimal situation. A sensitivity analysis shows that most parameters with a strong influence on the break-even willow price have reasonably high certainty. An uncertain value with strong influence is the willow yield without hydrological constraints, which could not be estimated from practical data. Methodological limitations of the study, both in the financial comparison between willow and grass, and in the yield estimations, are also discussed.