Numerical studies are reported for steady free convection in a horizontal porous cavity with localized heating from below. The central portion of the bottom surface is isothermally heated while the rest of it and the vertical walls are adiabatic, and the upper surface is cooled at a constant temperature. The effects of the size of heat source are examined for Rayleigh number, Ra*, up to 1000. An increase in Ra* beyond zero, produces a plume-like flow above the heated region and an inverse stratification in the core. The first convective cell appears near the edge of the heat source. More convective rolls are then produced at higher Ra* provided the length of the heated segment is larger than the layer height. There is always an upper limit to the number of convective rolls as a function of the size of heat source, H//1. The heat transfer rate always increases with Ra*, but the conduction regime gets extended as H//1 is increased.