The present invention relates to the use of a porous silica particle as a plant growth enhancer, said porous silica particle comprises porous silica comprising a particulate metallic element. The invention also relates to a granular composition comprising a carrier material and one or more spherical porous silica particles embedded in said carrier material, wherein each spherical porous silica particle comprises spherical porous silica comprising particulate silver, and to the use of the granular composition as a plant growth enhancer.