Plant phenological observations are typically made on a few (undefined number) individuals from a range of species, chosen to represent the population of this species or the collective behavior of crop fields, meadows, and forests ecosystems. Observations of individuals from the same plant species are rare. Nevertheless, the focus on phenological events, and in particular their power to express the impact of climate change, has increased over the past decade. New questions concerning biological life cycles, seasonal growth, winter dormancy, and their manifestation in the phenology of the plant have emerged. Against this backdrop, observations of multiple individuals from single plant species, growing in the same local area, are poised to play an important role in answering these questions.