Sphagnum mosses are vital to bog ecosystems and are, therefore, target species for peatland restoration and paludiculture. Their establishment relies on consistent wet conditions and adequate nutrient supply. However, extreme climatic events, such as prolonged droughts, threaten Sphagnum establishment. To better understand the effects of water table fluctuations on the establishment of different Sphagnum species, we conducted a field experiment with stable and fluctuating water table conditions. After 1 year, we measured Sphagnum cover, lawn height (as a proxy for growth), carbon (C) accumulation, and nutrient stoichiometry of 12 species. Our results show that a stable water table facilitated Sphagnum growth during the establishment. Nitrogen (N) to potassium (K) and N to phosphorus (P) quotients were higher in the capitula biomass of Sphagnum in the fluctuating water table treatment. We identified two clusters of Sphagnum species: cluster 1, characterized by a low N:K quotient and higher C accumulation—indicating strong establishment potential—included Sphagnum palustre, S. fallax, S. fimbriatum, S. riparium, and S. denticulatum. In contrast, cluster 2 exhibited a higher N:K quotient and lower C accumulation—suggesting vulnerability to environmental changes during establishment—included S. fuscum, S. centrale, S. magellanicum, S. papillosum, S. rubellum, S. austinii, and S. squarrosum. Our results indicate that lawn species, particularly S. palustre, S. fallax, and S. denticulatum, are promising candidates for rapid Sphagnum establishment under wet and dry conditions. Even when exposed to water shortages, Sphagnum restoration and paludiculture can promote fast‐track C accumulation.