Poinsettia

Revised by Joey Williamson, HGIC Horticulture Extension Agent, Clemson University, 12/15. Originally prepared by Bob Polomski, Extension Consumer Horticulturist, and Nancy Doubrava, HGIC Horticulture Specialist, Clemson University. New 05/99. Images added 12/15.

HGIC 1561

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The poinsettia (Euphorbia pulcherrima) is the most popular flowering plant sold in the United States with more than 70 million sold nationwide each year. When South Carolinian Joel R. Poinsett (1779 – 1851), the first U.S. ambassador to Mexico, collected and introduced the poinsettia to the Bartram Botanical Garden in Philadelphia in 1828, it’s doubtful he had any idea how popular this plant would become. Robert Buist, a Philadelphia nurseryman and florist, saw the potential of the newly introduced poinsettia, and named it after Joel Poinsett.

These wild Mexican plants were 12 to 15 feet tall with only 1 or 2 stems. The red floral bracts were quite narrow and droopy as compared with those of modern poinsettias, and they had large open centers.

The true flowers of poinsettias, called cyanthia, are small clusters of yellow blooms in the open center of the red floral bracts. These small flowers have no true petals attached, but are surrounded by red colored bracts, which are actually modified leaves. These bracts evolved to have the red color to attract insects for pollination of the small flowers. Through modern breeding, the cyanthia are now held in tighter, smaller and less apparent clusters, which gives significantly more emphasis to the beautiful red bracts.

'Oakleaf' (developed in 1923) is the oldest named variety today, and was used as breeding stock in the early 1900’s. Poinsettias were also grown as cut flowers during the 1950’s, with the Paul Ecke Ranch in California being the leading producer, as well as the leading breeder of modern poinsettias. The Paul Ecke Ranch supplies over two-thirds of the poinsettias sold worldwide

Plant breeders have produced cultivars with many other colors besides the traditional red bracts, or modified leaves. Plants are available with white, pink, peach, yellow, marbled and speckled bracts. However, red poinsettias account for over three-quarters of sales, and 'Prestige' accounts for the majority of the red poinsettias sold in the US.

'Prestige' poinsettia is the most widely sold red because its stronger branches are less apt to break.
'Prestige' poinsettia is the most widely sold red because its stronger branches are less apt to break.
Joey Williamson, ©2015 HGIC, Clemson Extension

Selecting a Poinsettia

Consider the following tips to ensure long-lasting beauty:

  • Look for plants with fully mature, thoroughly colored bracts.
  • Select plants with an abundance of dark, rich green foliage all the way down the stem. The leaves and bracts should not be drooping.
  • Look for plants that are balanced, full and attractive from all sides.
  • Select durable plants with stiff stems, good bract and leaf retention, and no signs of wilting, breaking or drooping.
  • Choose plants with the yellow flowers in the center that are not quite open.

'Winter Rose Dark Red' Poinsettia.
'Winter Rose Dark Red' Poinsettia.
Joey Williamson, ©2015 HGIC, Clemson Extension

Keep Your Poinsettia Beautiful

To help your poinsettia thrive in your home during the holiday season, follow these tips:

Light: Set your poinsettia in a bright location so that it receives at least 6 hours of bright, indirect sunlight each day. Putting it in direct sunlight may fade the color of the bracts. If direct sun cannot be avoided, filter the sunlight with a light shade or sheer curtain.

'Peterstar White' Poinsettia.
'Peterstar White' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

Temperature: Excess heat will cause the leaves to yellow and fall off and the flower bracts to fade early. The daytime temperature should not exceed 70 °F. Do not put your poinsettia near drafts, excessive heat or dry air from appliances, fireplaces or ventilating ducts. Chilling injury is also a problem and can cause premature leaf drop if the temperature drops below 50 °F.

Water & Fertilizer: Poinsettias require moderately moist soil. Water them thoroughly when the soil surface feels dry to the touch. Never let the potting mixture completely dry out and never let the plant sit in standing water. When watering, always take the plant out of its decorative pot cover. Water until water seeps out of the drainage hole and the soil is completely saturated. Do not fertilize a poinsettia when it is in bloom.

'Jingle Bell Rock' Poinsettia.
'Jingle Bell Rock' Poinsettia.
Joey Williamson, ©2015 HGIC, Clemson Extension

Care After the Holiday Season

Around March to April, when the colorful bracts fade, prune the plant back to about 8 inches in height. Although the plant will look bare after pruning, eventually new growth will emerge from the nodes up and down the stem. Keep the plant near a sunny window and continue to water it regularly during its growing period. You can take the plant outdoors once the night temperature remains above 50 °F. Fertilize the plant every two to three weeks during the spring, summer and fall with a well-balanced complete fertilizer such as 10-10-10.

'Christmas Day' Poinsettia.
'Christmas Day' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

In early June, transplant the poinsettia into a container 2 to 4 inches bigger than the original pot. Use a soil mix containing a considerable amount of organic matter, such as compost, leaf mold or peat moss. Pinch back the shoot tips or prune back the branches. Do not pinch back after September 1. When night temperatures become cool, 55 to 60 °F, bring the plant indoors to a sunny location.

'Jingle Bells' Poinsettia.
'Jingle Bells' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

Reflowering a Poinsettia

Poinsettia plants can be brought back into flower next year, although this procedure is somewhat demanding. Poinsettia is a short-day plant, which means it needs a continuous long dark period each night to form its colorful bracts. Starting the first week of October (for an eight- to 10-week period) the plant must be kept in total darkness for 14 continuous hours each night. Keep the plant in darkness by moving it to a closet or covering it with a large box. During this period, the plant must also receive six to eight hours of bright sunlight daily. Depending on the response time of the particular cultivar, the plant will come into full bloom during November or December.

'Luv U Pink' Poinsettia is a hybrid that has been used both in October and early spring sales.
'Luv U Pink' Poinsettia is a hybrid that has been used both in October and early spring sales.
Joey Williamson, ©2015 HGIC, Clemson Extension

Problems

Pests that attack poinsettias are also common to many other plants. The most common insect pest is the whitefly. Other pests of poinsettia include mealybugs, soft scales and spider mites. Whiteflies and mealybugs can be easily controlled by either a soil drench with imidacloprid, or by using plant spikes containing imidacloprid that are inserted into the soil, such as Bayer Advanced 2-in-1 Insect Control Plus Fertilizer Plant Spikes. Spider mites are most safely controlled by sprays of insecticidal soap, such as Safer Brand Insect Killing Soap, Schultz Garden Safe Insecticidal Soap, Natural Guard Insecticidal Soap, Bonide Insecticidal Soap, or Espoma Earth-tone Insecticidal Soap.

'Cortez Burgandy' Poinsettia.
'Cortez Burgandy' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

Root rotting fungi can occur in overwatered or poorly drained soils. Several factors can cause premature leaf drop, such as temperatures dropping below 50 °F, poor light or poor nutrition. Keep the delicate colorful bracts well-protected from wind and cold rain.

'Ice Punch' Poinsettia.
'Ice Punch' Poinsettia.
Joey Williamson, ©2015 HGIC, Clemson Extension

'Red Glitter' Poinsettia.
'Red Glitter' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

'Visions of Grandeur' Poinsettia.
'Visions of Grandeur' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

'Orange Spice' Poinsettia.
'Orange Spice' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

'Peterstar Marble' Poinsettia.
'Peterstar Marble' Poinsettia.
Barbara H. Smith, ©2015 HGIC, Clemson Extension

Wild Mexican Poinsettia

Below is the wild Mexican poinsettia like the plants that Joel Poinsett collected in 1828. Unlike modern poinsettias, the center is very open, which exposes the true flowers, and the floral bracts are narrow and droopy. In it native habitat, these plants may grow to 12 to 15 feet tall.

Are Poinsettia Plants Poisonous?

Poinsettia plants are not considered toxic. Because of the milky sap, the taste of the foliage is rather unpleasant, and it would be unlikely that a child would consume a significant amount. However, consumption of foliage may lead to stomachache, diarrhea or vomiting. The milky sap can be a skin irritant and cause a mild rash. Wash the skin with soap and water. Additionally, if the sap contacts the eyes, it can cause irritation and reddening. Flush the eyes with water.

References:

  1. www.MayoClinic.org
  2. www.WedMD.com
  3. www.MedicineNet.com

Floral bracts and flowers of wild Poinsettia from the Western  coastal region of Mexico. Note the tall stems behind, which  may grow as much as 12 to 15 feet tall with one bloom per stalk.
Floral bracts and flowers of wild Poinsettia from the Western coastal region of Mexico.
Note the tall stems behind, which may grow as much as 12 to 15 feet tall with one bloom per stalk.
Joey Williamson, ©2015 HGIC, Clemson Extension

Plant Culture Excerpted from:

  • The South Carolina Master Gardener Training Manual, EC 678.

Plant History Excerpted from:

  • Personal communication & U-Tube interviews with Dr. James Faust, Horticulture Department, Clemson University.

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