Plant growth regulator (PGR) recommendations vary from species to species & with plant age but from a practical matter growers need to control plant growth across a wide range of plant species at the same time and as efficiently as possible. In practice, growers face two complicated situations on a regular basis (1) relatively small plantings of many different species and or varieties are in the same house at the same time, and (2) relatively small of plantings at different stages of development are present in the same house at the same time. The key complication in both cases is the small planting size. Because strictly adhering to label recommendations would require you to mix a separate batch of PGR for each small planting (for example 10-50 flats of each variety, species, or stage of development), it would be extremely impractical to control growth in this way. The approach used by more experienced growers involves using a single low concentration drench of a root-active PGR as the backbone of their program but varying the volume applied to each small block. The overall affect is that the grower is able to make a real-time decision and deliver a variable dose while moving from block to block through the house. In this way, a single formulation is used to deliver a variable dose based on the specific level of control needed for each small planting. For instance, using 1 ppm Bonzi, the grower will apply a light drench or sprench-type of treatment to flats that require light control and a heavy drench to blocks of flats that require more aggressive control. Blocks that require no control are bypassed.
More information
See the 2015-2016 New England Floriculture Guide for latest information on plant growth regulators. Ordering info
Richard McAvoy, University of Connecticut
