We report an investigation to understand the basic growth mechanism of family of perovskite oxide manganite of LaAMnO (where A = Ca, Sr; x = 0.3 and 0.5) nanostructures in cost-effective hydrothermal route, which adds a new dimension in the low-temperature range (230-300 A degrees C) synthesis route of complex oxide system. We adapt size, shape, and composition control issues in different doping regimes by means of a simple common synthesis route and tuning the ground state property of nanostructures of complex oxide manganite system. The general principle of growth of nanocrystals and its controllable length scale tailoring are explained and most importantly, how the amount of mineralizer tunes the shape and size of the nanostructures has been discussed. Mechanism of shape and size tuning followed by a phase diagram has been proposed. The quality of the grown nanowires was confirmed by the number of physical property studies, both in ensemble and single nanowire level, using spatially resolved tools and techniques. Understanding of detailed interaction mechanisms of perovskite oxide manganite is definitely promising for rationally designing various kinds of inorganic materials in controllable length scale via wet chemistry route.