Andrographis paniculata (Burm.F.) Wall ex. Nees is an important medicinal plant in ASEAN countries that drives a high demand in the worldwide medicinal plant trade due to its andrographolide content. To find out optimum lighting and culture conditions in vitro, seed cultures were grown on photoautotrophic (sucrose- free) and photomixotrophic (3% sucrose) media. Blue and red monochromatic LED lights were used at an irradiance intensity of 40 μmol m-2 s-1 for 20 days as an energy source. Photosynthetic responses were measured in terms of chlorophyll content and net photosynthetic rate. Morphological responses were measured in terms of leaf and internode count, shoot length, number of roots, root length, fresh weight, and dry weight. Results were analyzed using SPSS 11.5 software. Gas chromatography results show that net photosynthetic rate was higher under blue light while red light resulted in taller plants. Root count and root length were higher under red light by 11% and 9.7% respectively. Sucrose reduced the net photosynthetic rate under both light spectra. Furthermore, plants under photoautotrophic conditions grew taller shoots and higher fresh weight. However, photomixotrophic blue light plants showed the highest dry matter content. Spectrum- wise, red light plants have a higher dry weight but when sucrose was involved in the growing medium, blue light plants outweighed it by as much as 7.91%. This suggested hyperhydric tissues in other cultures. Photosynthesis is constrained often by the low concentration of CO2 in photomixotrophic cultures as sucrose has been observed to act as an osmotic agent in in vitro culture systems.