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Climate change-induced alterations to precipitation may affect the regeneration dynamics of plant species, with the occurrence of drought influencing germination and seedling establishment. In Mediterranean grasslands, typically dominated by C3 annual species, germination occurs rapidly once sufficient rain falls in autumn. However, a single large precipitation event may be followed by a dry spell, with possible consequences for vegetation composition and productivity. We investigated the effects of autumn-time drought on germination and seedling establishment, and the subsequent recovery potential, in semi-natural and sown pastures. Although the majority of grasslands in Portugal are semi-natural, sowing legume-rich seed mixtures is an increasingly common agricultural practice in Portugal. Our results show an overwhelming effect of autumn-time drought on seedling establishment, with the semi-natural pasture being more compromised than the sown pasture. However, after the recovery period, the semi-natural pasture exhibited tendentially higher aboveground biomass recovery than the sown pasture. The differential species sensitivity to autumn-time drought and subsequent implications for recovery potential may be important for the agricultural practice of sown pastures, justifying additional research for drought-tolerant cultivar improvement to maintain productivity with climate change.