Abstract: An artificial seed has a powder structure or powder padded layer as a sealing material for anti-contamination purpose. This powder layer, 2-30 mm preferably 5-20 mm in thickness, consists of numerous fine sandy hydrophobic particles. The openings among the particles are small and winding enough to block micro-organisms from penetrating this dry and nutrientless layer into the seed, but not enough to block the needed oxygen. The hydrophobic nature of the particles is also effective to block water permeation and microbes therein, but not effective to block the tissue to grow out of the seed. The powder layer can cover any exposed part of the artificial seed. For the artificial seeds with a water-proof tough shell, the powder layer covers only the mouth or mouths of the shell. But for those with a water-soluble capsule, or water-soluble film, it covers all over the contents of the seeds. In both cases, the powder layer is again covered with the water-soluble film to kept the powder particles in position.