Rooting hormones improve uniformity among vegetative cuttings
Rooting compounds are essential for rooting difficult-to-root annual and perennial bedding plant species and sometimes used for those that may be moderately difficult.
Rooting hormones come in various formulations and contain different ingredients and can most often be applied in one of three ways: quick-dips or dipping the basal or cut end of the cutting into the rooting hormone prior to sticking; stem base sprays; or post stick foliar sprays. Application methods most commonly observed among Michigan greenhouse growers is the quick-dips and post stick foliar sprays.
Read more at MSU Extension (W. Garrett Owen)