The aim of the study is to examine the influence of the outplanting time on the cultivation of the kelp Laminaria saccharina in the northwestern Spain, close to its southern limit of distribution in the North Atlantic coast. We compared two L. saccharina cultures outplanted in February and December. We found that the starting time of outplanting affects to the yield and the substantiality value, as well as the growth rate. The yield, the substantiality value and the growth rates of L. saccharina sporophytes obtained for the trial outplanted in December were significantly higher than those in February. These results can be mainly explained by the effect of temperature on the growth of L. saccharina sporophytes during cultivation. On the other hand, our results show that even in the southern limit of distribution of L. saccharina, the cultivation of this species was very profitable in high yield and quality. The aim of the study is to examine the influence of the outplanting time on the cultivation of the kelp Laminaria saccharina in the northwestern Spain, close to its southern limit of distribution in the North Atlantic coast. We compared two L. saccharina cultures outplanted in February and December. We found that the starting time of outplanting affects to the yield and the substantiality value, as well as the growth rate. The yield, the substantiality value and the growth rates of L. saccharina sporophytes obtained for the trial outplanted in December were significantly higher than those in February. These results can be mainly explained by the effect of temperature on the growth of L. saccharina sporophytes during cultivation. On the other hand, our results show that even in the southern limit of distribution of L. saccharina, the cultivation of this species was very profitable in high yield and quality.