Managing Perennial Plant Height By Filomena Tomanelli Yoder Canada P.O. Box 370, Leamington, Ontario. One of the greatest challenges facing today's perennial growers is the achievement of compact, flowering plants. To attain plant longevity, we keep them in the greenhouse longer, and for economical reasons, close together. This creates competition for light in the greenhouse and plants have no other choice but to grow upward. Personally, when I first began growing perennials, I wished that I had a complete list of varieties and analysis of how to control their growth. There are many ways of controlling plant growth: by means of environmental control, moisture control and chemical growth regulators. I've decided to focus on the use of growth regulators as growth control. It became evident to me that I should develop a chart myself. This table was the result of the following experiment. I chose to use those regulators most commonly used and those most available to me: A-rest, B-nine, and Cycocel. I conducted the experiment with 4 samples of 35 varieties and the objective of illustrating the effects of these growth regulators on these perennial species and cultivars both visually (pictures) and in chart form. I used concentrations of 30 PPM with A-rest, 1000 PPM with B-nine and 500 PPM with Cycocel. I planted healthy vernalized plugs in all-purpose soil mix. After planting, as a routine, I used fungicide drench and a fertilizer (10-52-10) at 300 PPM phosphorous to enhance root formation. I then began a regular feed program with 20-10-20 at 200 PPM + 5 PPM Iron Chelate. The plants were kept at 60 F until they were established and then I began applying growth regulator. Spray applications were made in early morning or late afternoon in order to prevent applications from drying too quickly. The table presented demonstrates some major differences caused by these growth regulators. I hope that this note will aid you in producing quality perennials. Several days ago, I read an article that said "people who garden for 45 minutes a week lower their risk of heart attack by 66 %". Society gives our industry the possibility to make it possible for others to relax and to relieve stress by bringing nature and color to millions of people. One of the most fascinating aspects of perennials is the array of colors they can produce. This becomes an important factor when we learn that 80% of purchase decisions are based on color and that the population with the greatest spending power is the 50+ years old segment. They hold most of the financial assets, own the most luxury cars, enjoy 88% of the luxury vacations and have more time on their hands to shop. This segment of the market is making perennial growth more demanding in our industry. It is for this reason that we must establish growing methods to enable us to produce more compact flowering plants in a limited space.