To increase our understanding of the influence of soil salinity on fine root growth, biomass partitioning and whole plant biomass of invasive woody species in arid regions of the US, we exposed Tamarix ramosissima cuttings to contrasting soil salinity levels. Current year cuttings were grown individually in pots containing sandy soil in a greenhouse and irrigated with field water (control), solutions containing 50, 100, 200, 400 and 600 mM NaCl by keeping constant water table depth of 40 cm. Fine root distribution (< 1 mm), biomass partitioning and whole plant biomass were determined after 1 year of treatment. Profiles of soil water content were similar among the treatments. Soil salt concentration was higher at the surface and increased with increasing salt concentration in the irrigation water. Fine roots proliferated at the 20–30 cm depth, where soil water was higher and salt concentration was lower. Leaf mass ratio and whole plant biomass were highest in the 100 mM treatment. The 50 mM treatment also had significantly higher biomass compared to the control. However, the 100 mM treatment caused mortality, while all plants in the control and 50 mM treatments were survived.