We describe some of the regulatory mechanisms found in the signalling networks that mediate plant plasticity in response to the environment. In the absence of the relevant environmental cue, the response is often actively repressed at multiple levels, including chromatin structure, mRNA stability and protein degradation. The environmental signal normally initiates several pathways that share signalling elements. Positive and/or negative regulatory loops are also activated. Such complex networks might provide robustness and buffer the system against environmental noise. Uncovering the functional significance of these networks is a timely challenge.