Premise: Climate warming has altered the start and end of growing seasons in temperate regions. Ultimately, these changes occur at the individual level, but little is known about how previous seasonal life history events, temperature, and plant resource state simultaneously influence the spring and autumn phenology of plant individuals.

Methods: We studied the relationships between the timing of leaf-out and shoot senescence over three years in a natural population of the long-lived understory herb Lathyrus vernus and investigated the effects of spring temperature, plant size, reproductive status and grazing on spring and autumn phenology.

Key results: The timing of leaf-out and senescence were consistent within individuals among years. Leaf-out and senescence were not correlated with each other within years. Larger plants both leafed out and senesced later, and there was no effect of size on growing season length. Reproductive plants leafed out earlier and had longer growing seasons than non-reproductive plants. Grazing had no detectable effects on phenology. Colder spring temperatures delayed senescence in two of three study years.

Conclusion: The timing of seasonal events, such as leaf-out and senescence in plants can be expressed largely independently within and among seasons and are influenced by different factors. Growing season start and length can often be condition-dependent and dependent on plant reproductive status. To more accurately predict species and community responses to environmental variation, knowledge about the drivers of growing season length of individuals is essential.

This dataset contains the variables used for analyses in the article "Spring and autumn phenology in an understorey herb are uncorrelated and driven by different factors". It contains data on plant phenology and size estimated from data collected in the field in southern Sweden in the years 2013-2015. It also contains information on plant reproductive status and incidence of grazing based on field observations.