A method for covering and enlarging individual seeds by a chemical process, comprising the steps of introducing said seeds into a first solution containing at least one gelatinizable compound and a catalyst for the decomposition of a further compound capable of giving off a gas, and then introducing the seeds thus treated into a second solution containing at least one salt causing gelatinization of said gelatinizable compound and said further compound for the simultaneous evolution of gas for inflating the individual seeds to foamed bodies.