Spring leaf phenology influences plant fitness and is highly sensitive to environmental changes. The spring phenological escape hypothesis posits that deciduous understory plants generally leaf out earlier than canopy trees to access a period of high light before the canopy closes. However, plants in different forest layers may respond differently to climate warming, which could lead to phenological mismatch between the understory and canopy species. Therefore, exploring the phenological sensitivities of plants from different forest layers is crucial for anticipating the effects of climate-driven phenological shifts. However, these types of studies are still scarce. Here, we conducted a twig experiment in climate chambers for eight tree species and seven shrub species growing in subtropical deciduous forests in the Shennongjia Mountains, central China. Specifically, we set up three treatments (control, warming, and shading) for five weeks to test the responses of the timing of bud burst and leaf unfolding, and the duration of bud development to different temperatures and light intensities. For shrubs, bud burst and leaf unfolding occurred earlier and the duration of bud development was shorter than these of trees. For both shrubs and trees, warming significantly advanced the timing of leaf unfolding and shortened the duration of bud development. Shading significantly delayed the timing of bud burst for both shrubs and trees. Shading also delayed the timing of leaf unfolding and lengthened the duration of bud development for trees, but did not significantly influence the two phenological metrics for shrubs. Tree phenology, as measured by all three metrics, was more sensitive to temperature than was shrub phenology. The timing of bud burst of shrubs was slightly more sensitive to light than that of trees. Our results indicate that shrubs leaf out earlier than trees in the same forest, which allows understory species to take advantage of the high-light resources before canopy closure. However, in our study, trees were more responsive to warming temperatures, suggesting that spring warming could advance canopy closure relative to shrub leaf phenology, potentially resulting in phenological mismatch between understory shrubs and canopy trees.