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A Brief History of the Poinsettia

Euphorbia pulcherrima, more commonly known as the poinsettia, is one of the most popular potted flowers in the United States.  The poinsettia is native to southern Mexico and is names after Joel R. Poinsett, the first United States ambassador to Mexico, who introduced the poinsettia to the U.S. in 1825.

Today it is likely that at least one poinsettia can be found in nearly every household and business during the December holiday season - after which most people discard their plants.

However, it is possible to keep the plant in good condition into March, maintain it over the summer, and reflower it for another year's holiday season. This process may seem overwhelming at first, but it can be easy and satisfying to keep and rebloom the same poinsettia year after year.

Reflowering Your Poinsettia

The reflowering process begins around the first part of April by reducing the amount of water given to the poinsettia.  Do not deprive the plant of too much water, however.  If the stem shrivels and dries, the plant will die.  Now is also the time to move the plant to a cool place, about 60 degrees F., where it will receive indirect light.

In May the remaining stems need to be cut back to about three to six inches above the soil.  This is a good time to re-pot the plant or separate the stems if there are several in the original pot.  Use a pot with good drainage and use a quality potting soil that has been pasteurized to kill any diseases.  (See Soils for Houseplants)

Place the plant in a sunny window location and water when the soil feels dry to the touch.  Fertilize every two to three weeks with a complete fertilizer.  Follow directions on the fertilizer label for flowering plants.

When the minimum outdoor temperature is consistently above 60 degrees F. (usually the first part of June in Iowa), it is safe to move the poinsettia outside to partial shade.  When the shoots begin to grow, watering frequency will increase.

The poinsettia plant will need to be pinched back to control the height and promote a fuller plant.  The first pinch should be done when the first shoots are several inches long, or around the first week of July.  Simply remove the upper inch of growth on each stem, leaving about four to five leaves per stem.  This promotes more branches and ultimately a fuller plant.  After pinching a milky white sap will be secreted.  It is a good idea to wash this off with a gentle shower from a hose.  A second pinching may be necessary in mid-August.

Toward the end of August and the beginning of September, bring the poinsettia indoors to a sunny location where the temperature is 65 degrees to 75 degrees F.

Poinsettias are what horticulturists call "short-day" plants.  This means that to produce flowers, they must experience days with less than 12 hours of daylight.  Most varieties of poinsettias require eight to ten weeks of short days to flower.  For full color before December 25, short days need to start in early October.  If you want your poinsettia to bloom earlier or later, simply adjust the initiation of short days.  Plants are attractive for four to six weeks after the target flowering date.

To initiate short days the plant must be in complete darkness from 5 p.m. to 8 a.m.  This can be accomplished by placing the plant in a dark closet or in a light-proof box.  Any light that is received during the dark period will delay flowering.

Light is still needed for growth, so the plant should be placed in a sunny location from 8 a.m. to 5 p.m.  Water is needed and fertilize every week according t the fertilizer label.

Once color is visible, it is not necessary to keep the poinsettia in complete darkness during the night.  At this time the plant will flower with any amount of daylight.

Poisonous Plant?

Poinsettias have been accused of being toxic.  However, laboratory studies have shown that the leaves, stems, bracts, and flowers are not toxic to people or pets.

Directions at a Glance

It may sound time-consuming and confusing at first glance, but being able to rebloom poinsettias for several years is a great accomplishment.  The following schedule may be a useful reminder.

April 1:  Reduce watering, 60 degrees F

May: Cut back stems to 3-6 inches above the soil.  Re-pot or separate if needed.  Place in sunny window and water when soil is dry to touch. (Root cuttings if desired)

June: Move plant outside.  Water and fertilize more frequently as plant grows.

July 1: First pinch.

September 1: Bring plant indoors to sunny location at 65 degrees to 75 degrees F.

October: Initiate short days (For mid-December bloom date)  Water as needed and fertilize weekly according to the label.

Courtesy of Garden & Greenhouse - November 2001