In previous work, we identified that exposure to limited water availability induced changes in cell wall composition of mature Helianthus annuus L. leaves that affected mesophyll conductance to CO₂ diffusion (g_m). However, it is unclear on which timescale these changes in cell wall composition occurred. Here, we subjected H. annuus to control (i.e. water availability), different levels of short-term water deficit stress (ST), long-term water deficit stress (LT), and long-term water deficit stress followed by gradual recoveries addressed at different timescales (LT-Rec) to evaluate the dynamics of modifications in the main composition of cell wall (cellulose, hemicelluloses, pectins and lignins) affecting photosynthesis. During gradual ST treatments, pectins enhancement was associated with g_m decline. However, during LT-Rec, pectins content decreased significantly after only 5 h, while hemicelluloses and lignins amounts changed after 24 h, all being uncoupled from g_m. Surprisingly, lignins increased by around 200% compared with control and were related to stomatal conductance to gas diffusion (g_s) during LT-Rec. Although we suspect that the accuracy of the protocols to determine cell wall composition should be re-evaluated, we demonstrate for the first time that a highly dynamic cell wall composition turnover differently affects photosynthesis in plants subjected to distinct water regimes.