Understanding coordination between above- and below-ground traits is crucial for interpreting plant establishment strategies in water-limited ecosystems. Here, we quantified biomass, morphological and physiological traits of Haloxylon ammodendron and H. persicum seedlings to evaluate establishment responses to groundwater depth (GWD) gradients under contrasting soil textures. Across treatments, deeper groundwater was associated with higher specific leaf area (SLA), greater plant size (height and basal diameter), higher aboveground biomass, and increased rooting depth and root biomass. In contrast, net photosynthesis measured in the late morning varied only slightly among treatments. Positive correlations between shoot and root traits (e.g., above- and belowground biomass, height, and rooting depth) indicate coordinated scaling of carbon acquisition and water uptake during establishment. This coordination, however, weakened substantially for Haloxylon persicum in clay soil. Under this soil texture, seedling performance declined and mortality occurred even at shallow groundwater depth, suggesting that fine-textured and salt-prone conditions can constrain root function and undermine wholeplant integration. Our results highlight that establishment success in groundwater-dependent drylands depends on coordinated adjustment of canopy traits and rooting capacity, and that soil texture can modulate or disrupt this coordination. These findings provide a trait-based basis for species site matching and for groundwater and soil management in desert shrub restoration.