When you walk into a farm market or garden store filled with compact, lush flowering perennials, you can conclude that those plants were treated with plant growth regulators. Without them, most of those plants would be twice as tall and suffering from flower "hang over".
Linda Kulp, Penn State Extension horticulturist, gives a "thumbs up" sign to a Michigan State Web site loaded with current information on PGRs. You'll find it at: www.hrt.msu.edu/florAoE/PGRinfo.
The site, organized by Michigan State Horticulturists Matthew Blanchard and Erik Runkle, provides research-based information on greenhouse use of PGRs to regulate height of floriculture crops. All of the information presented is from experiments performed at Michigan State University.
The objective of many of the experiments was to determine whether a plant growth regulator was effective on a particular species, rather than to identify a recommended rate. You'll also find a collection of PGR articles and other greenhouse management issues by clicking on Greenhouse Crop Production Articles.