Water is the most important and most common chemical used in plant nurseries. It is also the most dangerous chemical used. Insufficient water, excessive water, and poorly timed irrigation can all lead to poor-quality crops and unacceptable mortality. Anticipated future declines of water availability, higher costs to use it, and continuing concerns about irrigation runoff harming the environment also spur interest in making more efficient use of water in nurseries. This article discusses water management in container nurseries and its influence on weeds, insects, and diseases. It also provides guidelines for minimizing pest issues with proper irrigation application and monitoring. This paper was presented at the joint annual meeting of the Western Forest and Conservation Nursery Association and the Intermountain Container Seedling Growers’ Association (Troutdale, OR, September 14–15, 2016).