ZnO nanowires were grown on a ZnO:Al polycrystalline surface by using a hydrothermal growth technique. Details about the effects of the hydrothermal solution parameters (such as the curing time, curing temperature and solution molarity) and the physical properties of the solution (such as the structural characterization, surface morphology and optical and electrical properties) were determined for the ZnO nanowires. The diameter of the nanowires was increased with the curing time. The maximum transmittance was detected when the ZnO nanowires cured for 3 h. With the increasing hydrothermal growth time, the transmittance value of nanowires was decreased based upon a disorganized structure on the surface with the time due to the incline of the longer nanowires. Hence, the thicker nanowire formation affected the electrical resistivity and transmittance of the nanowires. The flower-like ZnO nanostructures were observed at the some parts of the film for the nanowires grown in 35 and 45 mM solutions. The flower-like structures had a length of similar to 4 mu m, a root size of similar to 1000 nm and a tip size of similar to 900 nm.