<p><?tk 4?>β-aminobutyric acid (BABA) is a powerful priming agent of plant defences, but its agronomic use remains limited by the growth delay induced after treatment. To better understand the physiological basis and temporal dynamics of this growth inhibition, we investigated the respective impacts of BABA on expansive and structural growth in linseed (<i>Linum usitatissimum</i> L.) using an integrated physiological and metabolic approach. Plant responses were monitored in hydroponically cultivated linseed plants exposed to continuous BABA treatment for 10 days. Fresh- and dry-mass relative growth rates were assessed at the whole-shoot scale and separately in young and mature leaves, while water content, osmotic potential, transpiration, and metabolic profiling were analysed to characterise plant responses over time. An early and transient inhibition of expansive growth was observed in young leaves between 0 and 2 days of treatment. This early response was associated with a rapid decrease in plant water content. Reduced transpiration and osmotic adjustment mechanisms involving the accumulation of osmoregulatory metabolites, including sugars, amino acids, and myo-inositol, contributed potentially to the progressive recovery of expansive growth after 2 days of treatment. In contrast, structural growth was only moderately affected at later stages of treatment. Multivariate analysis further revealed that metabolic reorganisation closely followed the successive phases of growth response to BABA, with young leaves exhibiting the strongest and earliest metabolic shifts. Overall, our results demonstrate a temporal decoupling between expansive and structural growth responses under BABA treatment and indicate that the induced growth delay is largely transient. These findings suggest that BABA application may have limited impact on final biomass accumulation when treatment duration is appropriately controlled, supporting the potential integration of BABA into sustainable crop protection strategies.</p>