Poinsettias

History Native to Mexico Joel Pointsett, the first U.S. Ambassador to Mexico, introduced poinsettias to the United States in He liked them so much that he took them back to his greenhouses in South Carolina and began giving them to his friends. New production techniques and hybridizing have improved poinsettias so they now hold their color longer, have larger bracts, are more compact, and they come in a variety of colors. Poinsettias are the highest selling potted flowering crop in the U.S.

Myths Rumored to be highly toxic, the poinsettia’s toxicity is exaggerated. According to poison control centers, a 50-pound child would have to eat over 500 poinsettia leaves to reach a toxic dose. While eating parts of poinsettias shouldn’t kill a person or an animal, it might cause nausea and induce vomiting. However, the flavor is so bad it stops most children or animals from chewing on the leaves.

Stages Vegetative Flower Bud Initiation Flower Bud Development Flowering

Vegetative Stage Late August Pot in a finishing pot, drench with fungicides. Promote vegetative growth by lighting plants from 10:00pm to 2:00 am Fertilize with 300 ppm nitrogen and potassium. Provide degrees F night and degrees F day temperatures September 5-15 Pinch the plant leaving 4-6 leaves Maintain high humidity Raise fertilizer to ppm nitrogen and potassium Maintain temperatures

Flower Bud Initiation Stage September Turn lights off and give plants short days 5:00 pm- 8:00 am Drop temperatures to F at night and F during the day Fertilize at ppm nitrogen and potassium Space plants 15 inches by 15 inches to avoid stretching

Flower Bud Development Stage October 10 Flower buds begin to develop Stop shading Temperatures are adjusted to F at night and F during the day Fertilize at a rate of 300 ppm nitrogen and potassium Drench with a fungicide to control root rot

Flowering Stage November 15 Finish plants by dropping temperatures to F at night to deepen bract color Reduce fertilizer to ppm nitrogen and potassium

Common Problems The most serious insect pest on poinsettias is the whitefly Other problems include: Poinsettia hornworm, fungus gnats, spider mites, beet armyworm, scale, various fungal diseases, Botrytis, root and stem rot, bacterial canker A clean, weed free greenhouse and a pest control program reduce insect problems Well timed fungicide applications and careful watering practices reduce losses caused by fungi

Poinsettia Flowering The true flower of the poinsettia is the small, yellowish structures that form in the growing tip known as cyathia Bracts, the colored leaves for which the plant is known, are modified leaves surrounding flowers that develop pigmentation in response to flower initiation

Pinching Pinching which is the removal of the growing tip, or terminal to encourage development of lateral (side) shoots Pinching can be done using a knife or by using fingers to “snap” the tip from the plants A soft pinch will include removal of the tip and small, immature leaves only Today’s poinsettias respond best to soft pinches that stimulate side shoot growth from young stem tissue