Plant development occurs as an interplay of signalling, growth, and environmental cues, becoming a highly dynamic and complex system. In our lab, we study the dynamics of plant developing tissues, combining mathematical modelling, confocal microscopy, and quantitative image analysis. In this talk, I will first explain how cells become different from one another as they divide and grow in the Arabidopsis plant sepal, focusing on the case of giant cell patterning. I will demonstrate that giant cells appear in a random spatial pattern and become clustered while the surrounding cells divide. This finding shows that cell proliferation can have a fundamental role in shaping spatial patterns. Secondly, I will present our work on the dynamics of the floral transition in Arabidopsis, by which the plant changes from producing leaves to producing flowers. Our results indicate that a time-dependent bistable switch underlies the floral transition dynamics, leading to a critical slowing down and introducing an unexpected timescale on the transition. I will also discuss how this behaviour relates to the transition robustness and its reversibility.