Resumen: Planting mangroves is a conservation activity pursuing the long-term goal of sustaining the basis for fishing activities. The decision to engage in mangrove planting requires trading off the short-run costs of planting with its long-run benefits. We report a lab-in-the-field experiment with Thai coastal villagers in which we elicit short- and long-run time preferences prior to mangrove-seed planting. We show that less present-biased participants plant more seeds, while planting is unrelated to individuals’ future discounting. Our results contribute to the debate on whether present bias is positively or negatively related to conservation behavior by showing a positive relation in a replenishment act.