Abstract: A flexible form assembly for forming concrete structures during setting of the concrete is provided. The flexible form assembly includes an elongated form having a front side for engaging the concrete and a rear side. The rear side includes a back wall disposed between two rearwardly extending top and bottom walls which, in turn, are connected to downwardly and upwardly protruding lips respectively to form a C-shaped pocket for receiving a stake holder. The stake holder includes right and left flanges that abuttingly engage the back wall and that fit between the top and bottom walls and that are partially disposed between the upper and lower lips and the back wall. The stake holder further comprises a pocket portion that is connected to and disposed between right and left flanges. The pocket portion extends outwardly to define an apex which provides a looped pocket for receiving a stake.