Tip of the Week: Points About Poinsettias

Posted in Gardening Tips on January 4 2010, by Sonia Uyterhoeven

Sonia Uyterhoeven is Gardener for Public Education.

They are ubiquitous during the holiday season…and for good reason. Poinsettias (Euphorbia pulcherrima) are full, colorful plants with an enormous amount of festive appeal. As many of my botanically savvy readers know, the flowers are actually minuscule. The beauty of the poinsettia comes from its large, colorful bracts.

My personal delight with poinsettias is that they come not only in the traditional yuletide red but also in cream and rosy-pink. Whatever your taste, they seem to adorn every church altar and brighten up many homes at this time of year.

I cringe, though, when I see people walking down the street with an open poinsettia in hand, exposed to the elements. Please be an informed shopper and insist that the florist or retailer wraps the plant. This can simply mean temporarily covering the plant with a shopping bag. Remember that this tropical plant cannot handle cool temperatures.

Poinsettias are ideal for indoors, being happiest in temperatures from 60°F to 70°F. They get stressed in temperatures below 50°F. If exposed to cool temperatures and winds for a long period of time, the plant will collapse from frost damage.

Poinsettias prefer bright, indirect light and should be watered when the soil is dry to the touch. Avoid placing them in drafty areas or where there is excessive heat (a general rule for all of your houseplants), and remember not to place them near a fireplace or on appliances (again, a heat issue).

A final caution: Do not overwater your poinsettia or let it sit in standing water. Some of you may be appalled by this suggestion and insist that you never let your plants sit in water. But may I remind you that many holiday plants are wrapped in shiny green or red foil, hiding the plastic pot beneath but also preventing good drainage, hindering air circulation, and blocking light from the bottom foliage.

If you do decide to leave the foil on, here is my advice.

1. Fold back the top of the foil so that it does not obstruct the bottom foliage.
2. Remove the pot from the foil when watering, and let the water drain completely before placing the pot back into the foil. This may seem cumbersome, but this simple step will increase the longevity of your plant.

At this time of year, poinsettia owners are faced with a decision: either treat the plant as an annual and dispose of it, or keep it as a houseplant and try to get it to re-flower next holiday season.

You will be relieved to know that the answer is, without a doubt…throw it out! Here is why: Keeping your poinsettia takes a commitment of time. Once the bracts start to fall off, you need to reduce watering and let it go dormant (don’t let it dry out completely). Store it in a cooler location (60°F). In late May repot it and cut it back to about 6 inches.

During the summer, pinch it several times to encourage branching (just as you would a chrysanthemum). Start in late June or early July and then repeat in August. Put your poinsettia on a fertilizing regime that is consistent with your other houseplants (every 2–3 weeks) during its growing season.

Here is the catch: the poinsettia is photoperiodic, meaning it needs shorter days (or longer nights) to trigger the formation of flower buds (and the formation of the bracts). If you want holiday blooms, starting in October you will have to place your plant in a dark closet for 14 hours and back out into bright, indirect light for the remainder of the day. Back and forth you will go for at least 40 days and 40 nights—generally it is suggested from October 1 until Thanksgiving. (Some of the newer cultivars have been hybridized to produce the colorful bracts within the normal day length in fall, making re-flowering much easier.)

So, what have you decided? Something tells me that the poinsettia growers across the nation will sleep soundly tonight and for many nights to come with the knowledge that the vast majority of you will be back next year purchasing poinsettias. Happy January! (Please do send comments telling me what you’ve decided to do!)