Easter lilies (Lilium longiflorum) cultivated in the greenhouse industry are often treated with plant growth regulators (PGRs) to control their height by reducing stem length. A greenhouse study was conducted to examine the effects of uniconazole “Sumagic” on the growth of a new cultivar of Easter lilies ‘White Spring’. Treatments consisted of five bulb sizes based on circumference (12/14, 14/16, 16/18, 18/20, 20/22 cm) and uniconazole rates of 0, 2.5, and 5.0 mg•liter-1 with eight replications. Data collection consisted of stem height measured weekly, days until anthesis, number of flowers, and phytotoxicity rating. The results of the study showed a relationship between the uniconazole treatments and plant height, control plants had a greater average height (57.8 cm) than the bulbs soaked in 2.5 and 5.0 mg•liter-1 uniconazole, (33.5 cm) and (23.8 cm), respectively. Plant heights were also influenced by bulb size as they increased in height with increase in bulb circumference. The average number of days until anthesis increased with smaller bulb circumference, as anthesis was delayed. Days until anthesis were also affected by the uniconazole treatments, the bulbs treated with 2.5 and 5.0 mg•liter-1 solutions took approximately 6 and 8 days longer, respectively. Phototoxicity effects displayed as chlorosis on leaf tips and margins occurred in both the 2.5 and 5.0 mg•liter-1 solutions with symptoms more prominent in larger bulb sizes.
