A sustained-release granule of sugar comprising a core comprising primarily one or more of a monosaccharide, a disaccharide and a trisaccharide and an outer film comprising 10-90% by weight of an ethylene-vinyl acetate copolymer and 90-10% by weight of a wax. This sustained-release granule of sugar may be prepared by coating a core comprising primarily one or more of a monosaccharide, a disaccharide and a trisaccharide with a coating material comprising 10-90% by weight of an ethylene-vinyl acetate copolymer and 90-10% by weight of a wax by spraying a solution of the coating material onto the core while tumbling or fluidizing the core. The sustained-release granule of sugar can be applied in an artificial seed comprising an active plant tissue and the sustained-release granule of sugar which are encapsulated in a gel matrix.