PURPOSE: To easily obtain the title seeds by sterilization of the original seeds through a combination of a specified sterilization method with a second method using an acid.

CONSTITUTION: Sweet basil seeds are first immersed in a ca.1 N HCI for about 20min. and then further immersed in an aqueous solution of benzalkonium chloride diluted by a factor of 100-200 (Osvan solution) for ca.30min. The resulting seeds are then further immersed in ca.1 N HCl for about 10min to hydrolyze the polymeric compound on the surface of said seeds followed by immersion in ca.70wt.% ethanol. Thence, the resulting immersed product is immersed in a NaClO solution diluted by a factor of 2.5-5 for about 60min and then washed with a sterilizing water, thus obtaining the objective sweet basil seeds ca.4% in contamination rate.