SYNOPSIS Oldman saltbush (OMS) is susceptible to moisture stress during the seedling phase in spite of being very drought resistant when mature. Terrasorb, a starch based polymer with a high water holding capacity, was premixed with two soil types and its effect on OMS seedlings was investigated at three moisture levels. Plant available water (PAW) was increased significantly in both soil types which could have a positive effect on both irrigation frequency and labour requirements. In sandy soil Terrasorb use increased the above ground phytomass but root mass was reduced, except where moisture stress occurred. In clay soil the opposite occurred with an increase in root mass and a reduced above-ground phytomass—except where moisture stress occurred. The effectivity of Terrasorb depends on the moisture regime and it should not be used in heavy soil except where moisture is limiting.