Abstract. The effect of different bulb cooling periods (12, 14, 16 and 18 weeks) on some tulip varieties was examined. The cooling duration affected forcing period, and the length of stem and flower. Tulips forced from bulbs cooled for a longer time flowered earlier, were higher and had shorter flower buds.

The effect of cooling duration on growth and decorative value of some varietes of potted tulips

Summary

Four cultivars of tulips in pot production were used in this experiment. The bulbs were cooled at +9°C during 12, 14, 16 and 18 weeks. The effect of cooling duration of tulip bulbs on growth and flowering was investigated.

The results showed that longer cooling bulbs accelerated flowering. Increasing cooling period from 12 to 18 weeks causes lengthening of tulip stems. Flower bud length decreases with increasing length of cooling period. Tulips obtained from bulbs cooled for 12 to 14 weeks had the best decorative value.