Adapting Flax Production to Climate Change: Can a Spring Variety Be Grown in Winter?

Along the French-English Channel coast, fibre flax is traditionally cultivated in spring during a short window from March to July. However, increasingly frequent and severe spring droughts, driven by climate change, cast doubt on the sustainability of this practice. One possible adaptation, inspired by the winter cultivation of oilseed flax and tested over several years, involves extending the growing cycle by cultivating fibre flax in winter. In this system, seeds are sown in autumn, and the crop is harvested in early June. After four consecutive years of monitoring yield and fibre mechanical properties, a selected spring flax variety was grown both in winter 2022/2023 and in spring 2023 for direct comparison. This period included a mild winter favourable for winter crops, and a spring drought that severely impacted spring crops. Plants from the winter crop produced twice as many fibres at mid-stem height as the spring crop, but the mechanical properties of the elementary fibres remained similar in both. However, the elementary fibres in the lower stems of the winter crop averaged only 15 mm in length, compared to 33 mm for the spring crop, which benefited from higher temperatures. Regarding biochemical composition, lignin content in winter flax scutched fibres was significantly higher than in spring flax, at 4.2% versus 2.7%. Cultivating a spring flax variety in winter is thus feasible under favourable conditions, but the resulting fibres are shorter and more lignified, which may pose technical challenges during spinning and could require separating fibres from the lower stems of winter plants to ensure consistent fibre quality. In the final section of the paper, strategies to adapt flax cultivation to climate change are proposed, drawing on the experimental results and current meteorological projections, providing guidance for optimizing crop performance.