Stem strength of poinsettia

J. S. Kuehny, Louisiana State University
P. C. Branch, Louisiana State University
P. W. Adams, Louisiana State University


Poor lateral stem strength of poinsettia has been an increasing problem leading to commercially "unacceptable plants. Lateral stems tend to break from the main stem as plants reach maturity. The effects of constant versus adjusted fertilization rate, fertilizer type, plant growth regulator application, node number, and cutting stem diameter on poinsettia stem strength were investigated. A force gauge modified to clamp to the lateral stem of a poinsettia was used to determine lateral stem strength. The greater the lateral stem area, the smaller the lateral angle and the higher the lateral on the main stem, the stronger the stem strength. Poinsettias that had the greatest stem strength were fertilized with a fertilizer high in nitrate nitrogen and calcium, had no plant growth regulators applied, had a low number of laterals, and had a large stem cutting diameter.