This presentation introduces the concept of phenology and its practical application in landscape and nursery weed management. The presentation explains how observing plant growth stages and calculating growing degree days can help professionals accurately time preemergence herbicide applications for maximum effectiveness. It covers the science behind phenology, dormancy, and climate-driven plant behaviors, while highlighting online tools and resources for tracking seasonal changes. Emphasizing integrated strategies, the talk demonstrates how leveraging natural cues can improve weed control, reduce costs, and promote sustainable practices in ornamental plant care.