Poinsettias- how to keep them alive

If you got a poinsettia for Christmas you may be wondering if you can keep it as a houseplant. Some people enjoy the poinsettia until it starts looking bedraggled and then throw it out. But if you are a true plant lover and you can’t stand to see a plant die, you can keep your poinsettia as a houseplant and even get it to “bloom” again. The plant will stay pretty a long time, so enjoy it, but if you want to keep it thriving you’ll need to treat it as a plant and not a decoration.

Poinsettias, (Euphorbia pulcherrima), are native to Mexico.   They are large shrubs when mature, 6 or more feet tall.  The colorful part of the plant often referred to as the flower is actually the leaf bracts.  The flowers are the round, yellow structures in the center of the colorful area. The yellow comes from the plant pollen and after it is gone the colored bracts usually drop off.   Poinsettias now come in a variety of colors besides red, such as white, pink, yellow and lavender.  There are even speckled and multi-colored bracts (but no poinsettia has natural glitter on those bracts).

After the holiday

To keep your poinsettia thriving first remove the foil wrapper around the pot and make sure it has drainage holes.  If it does, get a saucer for the pot.  If it doesn’t have drainage holes either make some or put the poinsettia in a pot that has good drainage.  Don’t cut the plant back right now- this is sometimes recommended because older varieties of poinsettias were often lanky.  Modern varieties are usually more compact and greenhouses pinch them back if needed to produce a well branched plant. 

Place the poinsettia in bright light – it doesn’t have to be in a south window but the brighter the light the better.  Let it dry slightly between watering’s but keep it from wilting.  Dry air may cause the plant to lose leaves.  Misting isn’t recommended anymore but since dry air is also bad for you adding a humidifier to the room may help both you and the plants.  Rooms with lots of plants or a fish tank are generally humid enough.  A jar of water over a heating vent can also help. 
Hopefully you keep your home between 55 and 70 degrees.  Cooler nights are helpful for almost all species of plants, including poinsettias.  Ideally night temperatures should be about 10 degrees cooler than day temperatures in the winter for poinsettias.

In March begin fertilizing the poinsettia when you fertilize other houseplants or every other week. Poinsettias do best with a summer outside, but people have managed to keep them indoors year round.  After all danger of frost has passed move the plant outside- and now cut the plant back by one third.  This encourages new branch formation and keeps the plant compact.  Move the poinsettia to a shady location first, then gradually into full sun.  Don’t forget to water it.  It’s probably best to sink the pot into the ground, but not plant it directly into the garden. Fertilize the plant at least once a month.

If you are keeping the plant indoors cut it back by one third in June and make sure it’s in a warm, very bright location.  Air conditioning may confuse the plant, as the days are supposed to get warmer as they get longer and the sun brighter.  Air conditioning may also make the air drier, so watch the humidity level around indoor plants.

How to bring back poinsettia color

In the fall, before frost, bring any poinsettias outside back inside to a place where it gets bright natural light in the day but no artificial light at night. You may have to put a box over them when it’s getting dark outside.  Leave the plant in darkness until natural day break.   Poinsettias need a natural rhythm of shortening days to start the color show.  From mid-September to December they need 10-12 hours of darkness each day.

Older poinsettia varieties were very sensitive to light rhythms and a few minutes of light during what should be a dark period would greatly delay the coloring up process.   Modern varieties are not quite as sensitive and some plants will get some light coloration without short day periods. Sometimes a plant in a window will develop color on the window side of the plant, but not the side facing the room if the room is lit at night.  But if you want lots of color you need to manage the dark period so the whole plant is in complete darkness at night.  Cooler night temperatures from the day temperature aid the color process also.

If you are lucky the poinsettia leaf bracts will color up again.  The brighter the light in the day period the more colorful the bracts will become.   Once the color has developed you can move the plant to a more visible location for a few weeks if you want.   Even without much color the poinsettia can be a pretty houseplant if it’s grown well.

Well grown poinsettias will get larger over the summer.  You may have to move them to a larger pot in the fall but don’t trim the plant back then.  Wait until after “blooming”, preferably as the days are starting to get longer, to prune them back.

Poinsettias are mildly toxic, so keep children and pets from nibbling them.   They probably wouldn’t die from the experience but might have a lot of stomach discomfort.  Poinsettia problems include over-watering, causing root rot, and powdery mildew, usually from cool, too humid conditions or misting the plants.  Correct the watering or humidity to save the plants.  Typical houseplant insects like whitefly and spider mites occasionally affect poinsettias in the home.  Treat infected plants with houseplant insecticides if this happens.


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