Seeds of cyclamen `Laser Scarlet' were germinated at 20C in darkness. Four weeks after germination, the seedlings were moved to a greenhouse at 20C and 16 hours daylength and 4 weeks later transplanted into 10 cm (520 cm3) pots. Plants were grown under 8 or 16 hours daylength in combination with 3.0, 7.5 or 12.0 mol·day-1m-2 for 9 weeks after transplant. The instantaneous irradiance was adjusted based on photoperiod to provide the desired total daily irradiance levels. After the 9 weeks photoperiod and irradiance treatment, plants were allowed to develop and flower at 16 hours daylength, 7.5 mol·day-1m-2 (130 μmol·s-1m-2) and 15C. There was a trend for an increased number of leaves for cyclamen grown at higher total daily irradiance levels at either 8 or 16 hours photoperiod. The largest number of leaves (14 ± 2.2 leaves) after the 9 weeks was observed for cyclamens grown at 16 hours photoperiod and 12 mol·day-1m-2 (210 μmol·s-1m-2). The plants grown at the longer day length and highest irradiance level also, accumulated most dry weight (92 ± 18.7 mg) during the 9 weeks of photoperiod and it-radiance treatment.