The hydroponic device contains support members, at least a frame member placed on the support members; a cover member placed on the support members covering the frame member. The frame member contains a base element and a number of extension elements. The base element is for the installation of an absorbing piece where seeds are placed. Each extension element has at least a through slot where a positioning pin of the base element or a previous extension element is slidably embedded. The base element and the extension elements are as such collapsible and expandable along a lateral direction on the support members so as to provide room of growth for the seeds.