||Long day promotes flowering of Gysophila paniculata L cultivar ‘Bristol Fairy’. Repeated treatments with GA3 or GA4 + 7 in short days did not promote flowering. The long photoperiod is effective only at relatively high temperatures. At night temperatures below 12°C, the plants remain vegetative even in long days. Efficient artificial lighting is from incandescent lamps at 60–100 lux. Fluorescent lighting (Cool-White) is not effective. Lighting of 4 hours as a night-break or at the end of the night were equally effective, but 4 hours lighting as a day-extension was less effective. Whole-night lighting promoted flowering more than any of the 4-hour lighting regimes. Cyclic lighting of one third light in each cycle promoted flowering to the same extent as continuous lighting. Light intensity during the day has a decisive effect on flower production.