Floating coastal structures, considered as an alternative to land reclamation for expanding livable space, are regarded as cost-effective and sustainable solutions for land-scarce cities. Among these structures, floating planters stand out for their ability to enhance the aesthetics of water bodies, provide habitats for aquatic organisms, and reduce land usage. Despite their advantages, there is a dearth of research and engineering guidelines for the design and construction of floating planters. In this research, a preliminary design of a cylindrical floating planter is proposed, and its stability and hydrodynamics in still water is analyzed. The planter consists of an inner steel skeleton and an outer UHPC skin. The cylinder is 5 m in diameter and 5 m in height. The overall weight including ballast, soil and trees is about 699.5kN. For the stability analysis, the wind loadings on the coaxial branched trees are considered. With appropriate weight distribution and ballast, the stability of the structure is analyzed and verified under designed wind condition in still water. The Runge–Kutta Method is used to obtain the motion response of the floating planter by solving the six-degree-of-freedom motion equation. The results showed that the natural periods are 4.2611 s for the heave, 11.0291 s for the sway and 5.5655 s for the roll, which agree well with the theoretical predictions. Further study is still in demand to analyze its motion under design wave conditions.