Wednesday, October 7th, 2009...12:00 am

Getting Poinsettias to Turn Red

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Poinsettia flowers, after blooming by Martin LaBar

Poinsettia flowers, after blooming by Martin LaBar

TheGardenLady received this question from John:

I have a Poinsettia that I kept outside in a 12″pot from last Christmas. The plant has gotten pretty big and nice green color with no pruning. What can I do to this Pointsettia to get it to turn red?  Or am I too late?

You may be just a little late in starting to acclimate the Poinsettia to enable the bracts (those are the leaves that look like petals ) on your Poinsettia to turn red by December and to get flowers. Even if you start now and are lucky, the plant may not have the red bracts and flowers until Valentine’s day. Since having a healthy plant is part of the battle, it is worth, at least once, to try to convince the plant to give you the color you want even if you start late. If you don’t have success this year and the plant continues to be healthy and has no insect infestation, don’t toss the plant, but try again next year. Try starting the regimen a little earlier to see if you can do it.

It takes some effort and pampering to make the plant get those red bracts and bloom a second time – something that nurseries do in light and temperature controlled greenhouses where they have the needed equipment and a crew to do the work; but some people have had success in the home.

You should have taken your plant indoors by the end of August, or around Labor Day, if your area has days or nights that dip below 55 degrees.

Do Not REPOT your Poinsettia at this time of the year. Any repotting should have been done in late spring. Do NOT prune the Poinsettia now- it will NOT tolerate severe pruning at this time of the year. If it needed pruning, the last pruning should have been done by early July.The only thing you do to your plant now is to clean the plant by trimming away dead leaves or dead stems if it needs it. Otherwise, don’t cut anything.

If you want the Poinsettia to have red bracts, NEVER leave the plant outdoors if the temperature drops below 55 degrees. And when you take the Poinsettia indoors keep the plant in a temperature that is between 55 to 62 degrees. Never let the plant dry out or stay saturated. Keep the plants set on stones in a tray with water so that they have humidity; otherwise leaves will drop and it won’t flower. Never put the plant where there is a draft.

To bloom at Christmas time, starting from September 21st to the beginning of October, Poinsettias need a controlled period of Complete Darkness at night, every night – no light should leak, not even a little light. Keep the plant in the DARK for anywhere from 13 to 15 hours for eight to ten weeks. An UNUSED closet is a good place to put the Poinsettia at night. Tape the door shut so no one can peak and tape any places where light might get through. If there is a crack under the door where light gets in, it will not allow the plant to flower and get red bracts. Tape that crack. Or if you have a dark box that does not admit light, put the plant in it and cover it with a black blanket so no light can get in. The plant wants those 13 to 15 hours of Total, Absolute Uninterrupted Darkness. Greenhouses have thick black cloths to cover the flowers so that nothing, not even a passing car, will shed a bit of light on them. The darkness must be complete darkness; any light leaking in, even a tiny amount, will interrupt the cycle and add days to the period leading up to “flower” formation

Then in the daytime the Poinsettias need Very Bright light- at least 6 hours of controlled very bright light with a few hours of direct sun. In the daytime you can put the Poinsettias outdoors if the temperature is around 60 degrees. If the temperature is colder than that, the plant should be indoors in your brightest window.

Do this every day and every night for up to 10 weeks. After 5 to 6 weeks you should start to see the red bracts emerging from the growing tips of the Poinsettia plant. Beginning by the first of October should give you late December color.

I asked a gardening friend if she does this and if she has success getting her Poinsettias to rebloom. She said she tried this one time but it was so much work that she now allows her plant to bloom whenever and if it wants. And every Christmas season she goes out to buy a new Poinsettia. “They are so cheap and it is so much easier,” she said.

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2 Comments

  • Thought you would like to know I have managed to get the red leaves and bracts! I am so thrilled I have tried for a couple of years and no success. This year I tried a B&Q rubble black sack and it worked. I started at the beginning of September and am now wondering how much longer I need to keep covering it up at night?

  • I regenterated two smal pointsettas

    They both huge I began to put in total darkess on Oct 1 now is December 8 and only the very new younger leave turn Red

    What did I do wrong And what can I do to turn all leaves red I would so love to know from you.

    Thank you so,

    Edward

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