In Madonna lily (Lilium candidum L.), the influence of the bulb size (circumference), temperature and length of cold treatment, and culture temperature on flowering was studied and the possibility of double harvesting was investigated. The minimum bulb size of Madonna lily for readiness to flower was about 5 cm in circumference. The bulb circumference yielding a high flowering rate and good flowering quality, with an about 80-cm plant height and around five flowers, was 10 cm or more for seasonal flowering and 20 cm or more for forced flowering at 4°C for 10 weeks. Furthermore, in the case of forcing, the possibility of producing a flowering bulb of a smaller size by carrying out two-stage cold treatment was recognized. Cold treatment of bulbs promoted shoot emergence and stem elongation, and 10-week cold treatment was sufficient for vernalization to flowering. The flowering rate with the 10°C, 10-week treatment was higher than that with the 2°C, 10-week treatment, but it was further improved by the addition of 2°C, 5-week treatment to 10°C, 5-week treatment. The marked requirement of chilling of a bulb for flowering at a 25°C cultivation temperature was suggested, and with cultivation at high temperatures, such as a constant 25°C or 35°C (day)/25°C (night), the abortion of flower buds and floral abnormalities occurred. Moreover, bulbs showing forced flowering within the year flowered again on receiving natural chilling and those flowering in January also did so with appropriate cold treatment. Therefore, on implementing forced culture at these flowering times, it was confirmed that flowers of Madonna lily could be double-harvested.