A significant reduction in the number of flowers (14) following 30% SH/30% SH/ND + 14HID and an increase in the number of flowers (22) when grown under 30% SH/ND or ND + 14HID during ST 2, ST 3 (Expt. 1) suggests that flowering is accelerated by low irradiance, while the number of flowers is increased by irradiance under ND or ND + 14HID. The effect of irradiance during ST 2 and ST 3 could be coupled with decreasing greenhouse temperatures,and the interaction between irradiance and temperature should be further investigated.