A study was conducted to examine the effects of different temperatures and water stress on Encholirium spectabile seeds. We evaluated the germination percentage, speed and time of germination of small (<2.97 mm), medium (2.97 ≤ M ≤ 4.01 mm) and large seeds (>4.01 mm), at temperatures of 15˚C, 20˚C, 25˚C, 30˚C, 35˚C, 40˚C and 45˚C and a photoperiod of 12 hours of light. Seeds were subjected to osmotic potentials of 0, −0.2, −0.4, −0.6, −0.8, −1.0, −1.2 and −1.4 MPa, induced by solutions of polyethylene glycol. The results indicated an excellent germination of medium and large seeds at the temperatures of 20˚C, 25˚C, 30˚C and 35˚C. The temperature of 35˚C provided the best mean germination time of large seeds and a higher speed rate of medium and large seeds. E. spectabile seeds germinate in a wide range of water deficit of −0.2 to −1.2 MPa. Germination reduced at concentrations of −1.0 and −1.2 MPa. No germination occurred at −1.4 MPa. Larger seeds showed the higher germination potential than medium and small seeds at the temperatures of 25˚C, 30˚C and 35˚C and in the range of water deficit of −0.2 to −1.2 Mpa.