February 2008 issue of the Cornell Flower Bulb Research Program Research Newsletter:
Height control, especially in the postharvest phase, remains a potential problem in hyacinth. During forcing, hyacinths are commonly sprayed with Florel for height control, and to reduce stem floppiness. Rates are commonly in the range of 1,000-2000 ppm, for 1 or 2 sprays. While generally effective, some growers report problems with Florel sprays, including lack of effect and non-uniformity.
Read the whole article. Starts on page 3.