Understanding the dynamics of capillary flow through unsaturated porous media is very important for the development of an effective water and nutrient delivery system for growing plants in microgravity. Experiments were conducted on Mir Space Station with an experimental cuvette called “Capillary Testbed.” The results of these experiments showed a need for continued experimentation in microgravity and that major modifications to the cuvette were needed.Preliminary microgravity tests of the new, modified Capillary Testbed device were conducted during parabolic flights on KC-135. In spite of the short duration microgravity portion of a parabola, the performace of the modified Capillary Testbed was evaluated. An experiment was conducted on the Space Shuttle, STS-63 mission, using a modified Capillary Testbed device. This experiment studied the effect of bead diameter on capillary flow by comparing the capillary flow in three different granular beds. The preliminary results are discussed in this paper.