Since its introduction into North America over 170 years ago, the poinsettia has become a major ornamental potted plant, and is an important component of the U.S. floral industry. Susceptibility to insect pests and diseases caused by pathogens remains a problem for poinsettia production, even under greenhouse conditions. While chemical treatment can control certain insect pests and disease pathogens, such treatment can also have an adverse effect upon poinsettias. The methods described herein provide a means to genetically engineer transgenic poinsettia that express macromolecules capable of protecting the plant against the insects and pathogens. The production of transgenic plants can also be used to enhance the commercial value of poinsettia by controlling characteristics such as flower color.