Growth chambers are used by agronomists for various experiments on plants. Because light impinging on plants is one of the main parameters of their growth, inhomogeneity in light reception can provide large bias in the experiments. In this paper we present the first steps of a framework which aims at computing the best locations of light sources that could ensure an homogeneous lighting at some places in these chambers. For this purpose we extent the capabilities of a global illumination approach dedicated to growth chambers. We use Genetic Algorithms with simple source and material models in order to find good light sources locations. Our first results show that it is possible to find such interesting location and that they improve the lighting distribution on the experiment tables used in these chambers.