Refresher For Reflowering Poinsettias and Long Term Care

On By durhammastergardenersIn houseplants

By Wendy Diaz, EMGV

If you are like me you probably bought a big beautiful poinsettia (Euphorbia pulcherrima) in December for easy and festive home decorating over the holidays.  My poinsettia is doing quite well in my west facing picture window and because it is a relatively easy houseplant to care for I will probably keep it until spring and take it outside until the frost kills it in the fall and buy a new one in November. Nevertheless, a friend asked me how she would go about getting her lovely poinsettia to reflower next Christmas and keep it thriving until then. I decided, for my friend, to do some research and refresh my memory on the reflowering steps, because four years have past since my master garden training on this topic, and write a primer on the care of poinsettias.

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Several poinsettia plants in one pot placed by west-facing window.
Photo by Wendy Diaz, January 9, 2019

The following list of tasks will keep your poinsettia thriving until you want to prepare it to reflower.

Indoor Care of Poinsettia Plant

  1. Place plant in a bright window preferably south, east or west facing and temperatures between 70oF to 75 oF.
  2. Make sure temperature of room does not drop below 55oF.
  3. and avoid cool drafts. (Cover when purchasing them in the winter especially.) Conversely, temperatures about 75 oF cause bract fading and leaf drop.
  4. Water plant when needed, about once per week or when surface of potting soil feels dry (do not let plants dry out or lower leaves will fall). Do not over water because poinsettias do not like “wet feet”. Let them drain well before putting them back in their foil covering if the pot is covered with decorative foil.
  5. Remove the bracts (brightly-colored red modified leaves) when they discolor and wither.
  6. Apply half-strength fertilizer solution monthly.

Poinsettias are tropical plants originally from southern Mexico and Central America and temperatures below 55oF can damage the plants so when the danger of frost has passed, move it outdoors to a location that receives high indirect light (morning sun/afternoon shade). Then, if you have the dedication to get it to reflower you must complete the process of artificially lengthening its daily exposure to darkness for about a couple of months in the fall. The poinsettia is sensitive to the duration of light (day length) and it is a “short-day” plant whereby the shorter length of time the plant is exposed to light within a 24-hour period triggers physiological response of flowering. The sensitivity to day length is called photoperiodism. Figure 18-23 from the Master Gardener handbook shows the affect of only green foliage on poinsettias that are exposed to too much daily sunlight (less than 8 hours of darkness) during the fall period.

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Figure 18–23 from the North Carolina Extension Gardener Handbook Photoperiod demonstration on Poinsettia ‘Prestige Red’. Short Day exposure (right): More than 12 hours of darkness in a 24-hour period. Long Day exposure (left): Less than 8 hours of darkness in a 24-hour period2. Photo credit Diane Mays  CC BY – 2.0

 

 

 

 

 

Steps for Poinsettia Reflowering

  1. Place plant outdoors in high indirect light after danger of frost.
  2. Cut back the stems to 3 to 4 inches to promote new growth and encourage branching.
  3. Water and fertilize as in indoor care.
  4. Bring plant indoors when night temperatures fall below 60oF (near the end of September for Durham).
  5. On October 1, 2019, put the plant in 14 hours of uninterrupted darkness each day until bract color is well developed about mid- to late November. Put it in a closet of place a cardboard box over it. Any light during this time will delay flowering. See Figure below for affects.
  6. Night temperatures should be 60 to 70oF.
  7. Place poinsettia in maximum sunlight each day for 10 hours.
  8. Water the plants as needed for medium soil moisture.
  9. Fertilize every other week with a complete-analysis (20-10-20), water soluble fertilizer
  10. Plants should bloom (red bracts) after 9 to 11 weeks of short day/long night treatment.

I wish my friend and other intrepid houseplant gardeners success in reflowering their 2018 Holiday Poinsettia but as an outdoor person and due to lack of closet space, I will continue my tradition of keeping them outside between last frost in April and first frost in October, followed by a trip to a local grower to purchase new poinsettias in late November.  I am looking forward to new and interesting colors each new year brings.

References:

  1. https://poinsettias.ces.ncsu.edu/homeowners/home-growing-poinsettias/
  2. https://content.ces.ncsu.edu/consumer-care-of-poinsettias
  3. https://content.ces.ncsu.edu/extension-gardener-handbook/18-plants-grown-in-containers#section_heading_8773
  4. https://lee.ces.ncsu.edu/2015/12/poinsettias-16/

Further reading:

  1. https://durhammastergardeners.com/2018/02/14/my-poinsettias-survived-the-season-now-what/