1. This study deals with the effect of room and soil temperature on the growth and the quality of the cut flowers of forcing of tulip (an Early Single and Darwin Hybrids) with different flowering times.
2. The longer the number of days required for flowering after planting was, the larger the sum of the temperature. However, the average room temperature was lower than 12℃ for each forcing. The average room temperature for early flowering was higher than that for late flowering, which was in turn higher than that for normal flowering.
3. At the 1st stage (from planting to the 3rd week) the elongation of tulip per day was small regardless of the average temperature being high or low. The higher the average temperature at the 2nd stage (from the 4th to the 5th week) was, the larger the elongation, although the effect was small. The effect of temperature on the elongation in each forcing became remarkable at the 3rd stage (from the 6th to the 7th week) and at the 4th stage (from the 8th week to flowering), when significant elongation was observed even at low temperature.
4. The quality of cut flowers was slightly affected by a change in the number of days required for flowering under forcing, but there was no problem in marketing.
5. It is necessary to set a temperature suitable for the growth stage of tulip for the sake of the economy of electric or oil energy. The average room temperature from planting to flowering should be controlled at 11 to 12℃ for getting cut flowers of good quality. Taking the market price of tulip into account, the forcing temperature must flexibly be controlled during the 3rd and 4th stages.