Henophyton deserti Coss. & Durieu, is an endemic Saharan plant of the Brassicaceae family. Experiments were conducted to assess the effects of temperature and water stress on seed germination. The germination responses of the seeds of H. deserti in complete darkness were determined over a wide range of temperatures (10°C, 15°C, 20°C, 25°C, 30°C, 35°C) and different water potentials (−0.2, −0.6, −0.8, −1.0, −1.2, −1.4, −1.6, −2.0 MPa) induced by polyethylene glycol (PEG-6000) in order to verify their resistance to drought conditions. Germination was inhibited by either an increase or decrease in temperature from the optimal temperature (20°C) and decreased with a decrease in water potential at all temperatures. An interaction between water potential and temperature yielded no germination at −2 MPa. An understanding of these factors is crucial for successful regeneration and recruitment of these long lived Saharan plant species.