PROBLEM TO BE SOLVED: To provide a simpler hydroponic method.SOLUTION: There is provided a solid fertilizer composition for hydroponics in which solid fertilizers having dissolving ability corresponding to growth periods of a plant are combined, which contains a pH dependent slow-release solid fertilizer whose solubility varies corresponding to at least changes of pH. The solid fertilizer further contains a water-soluble slow-release solid fertilizer. A growth period of a plant is divided into three, an initial period, a middle period and an end period. As a solid fertilizer corresponding to each period, water-soluble slow-release solid fertilizer is used corresponding to the initial period fertilizer, and a mixed fertilizer of the water-soluble slow-release solid fertilizer and the pH dependent slow-release solid fertilizer are used corresponding to the middle period and the end period fertilizer.【課題】より簡便な水耕栽培方法の提供【解決手段】植物の成長期に応じた溶解能を有する固形肥料を組み合わせた水耕栽培用固形肥料組成物であって，少なくともpHの変化に応じて溶解性が変化するpH依存緩効性固形肥料を含むことを特徴とする水耕栽培用固形肥料組成物。固形肥料としてさらに，水溶性の緩効性固形肥料を含む。植物の成長期が，初期，中期，終期の３つに分けられ，それぞれに対応する固形肥料として，初期に対応する肥料として水溶性の緩効性固形肥料が，中期・終期に対応する肥料として水溶性の緩効性固形肥料とpH依存緩効性固形肥料の混合肥料が用いられる。【選択図】図１
