The effect of swelling ratio of a novel material as Hydrolysed Sulfonated Styrene Acrylonitrile Copolymer (HSSAN) on the emergence and growth of tomato and lettuce seedlings was investigated. Water insoluble polymers having various swelling ratios were incorporated into soil and quartz sand at a constant concentration of 0.15% w/w and growth curves were obtained for each case study. The data show that HSSAN having high swelling ability produced higher seedlings in a short time. High swelling ratio values reflect the amount of crosslinking agent needed for the preparation of the resin. Low cross‐linking agent concentrations are required for satisfactory results of the conditioner on soil substrate.