The present application is directed to a method and apparatus for monitoring soil hydraulic properties, and for collecting soil pore-water samples, in relatively undisturbed soil conditions, by means of a vadose zone probe (10) adapted to be mounted on an inflatable sleeve (18) for installation in a borehole (14) formed in the vadose zone, said vadose zone probe comprises a fluid cell (15) having one or more conduits (13a, 13b, 13c) connected thereto for externally accessing its interior, and a porous medium (11) installed in, or formed on, one of its walls for allowing passage of liquid between the interior of said fluid cell and the borehole soil, wherein said vadose zone probe is made from an elongated body having a front (10f) and rear (10r) sides, and wherein said rear side is substantially flat and said front side is made from a deformable and permeable material, or having a curvature corresponding to the curvature of said borehole.