Suaeda species are widely distributed in the coastal areas and are commonly selected as candidates for coastal saline–alkaline soil restoration. In this study, a pot experiment was carried out to investigate the effects of different nutrient levels and salt stresses on the growth and physiological characteristics of Suaeda salsa and Suaeda glauca, two coexisting species exhibiting a spatial segregation in the Yellow River Delta (YRD), China. Our results showed that both Suaeda species can adapt to a high salinity environment (21 g kg⁻¹ NaCl) and display similar regulation strategies, including increased shoot–root ratio, maintaining leaf succulence, and relying on proline and metal ions as osmotic regulators. However, nutrients had a different impact on the salt tolerance of the two species. Under low soil salinity levels, nutrient addition was more beneficial for S. salsa, while under high soil salinity levels, nutrient addition was more beneficial for S. glauca. Our results reveal that the spatial segregation of the two Suaeda species was not driven by salinity. Both species can be used in coastal restoration projects for their high salt-tolerant abilities, but the nutrient addition management should be specific to the species and site soil levels.