Although wetlands can sequester carbon dioxide through high productivity, they can also act as sources of greenhouse gases (GHGs)including methane (CH₄). The amount of GHGs produced exhibit high variability along with changes in temperature, water level, vegetation, and organic carbon content. In this study, we proposed wetland design with Sphagnum to inhibit GHGs emission. We used replicated wetland mesocosms to investigate relationships between contrasting soil conditions with different plant species, and methane and carbon dioxide fluxes in emergent marsh systems with or without Sphagnum. Methane fluxes were more strongly affected significantly by plant species than soil type. Mesocosms with Phragmites and Sphagnum exhibited the lowest rate of methane flux in all soil types. The highest rate of CO₂ uptake occurred in loamy sand and sandy clay loam soils with Phragmites. Implications for soil type and vegetation design of created wetlands with sphagnum are discussed.