Use of Growth Retardants for Floral Initiation of Hydrangeas

Abstract

Floral initiation was successfully stimulated for plants of Hydrangea macrophylla 'Rose Supreme' under non-inductive environmental conditions by spraying plants with XE-1019 or paclobutrazol. Effective treatments were 10 weekly of 5 biweekly sprays of 100 mg-liter ⁻¹ paclobutrazol; 5 biweekly sprays of 11 or 30 mg-liter⁻¹ XE-1019, and 4 triweekly (once every 3 weeks) sprays of 15 or 30 mg-liter⁻¹ XE-1019.