01 March 2010

Poinsettias

I know this may seem an odd time to talk about a plant that is traditionally a Holiday item, but many people still have Poinsettias in their homes after Christmas is over.  I thought I'd mention a bit about them, and a few tips on keeping them growing until the following season. 

Poinsettias (Euphorbia pulcherrima) are native to Mexico and can grow from 2 - 16 feet in height, although here in the Northeast, we typically see the shorter ones.  In places such as Florida, they can be grown as shrubs due to the warmer, year round weather.  I imagine they lost many of them this winter though with the frost, as Poinsettias cannot tolerate temperatures below 50 degrees.

The plant bears dark green leaves and brightly colored bracts, which many think are flower petals.  Actually, the bracts are colored leaves.  The leaves change color due to photoperiodism which means that the plant requires 12 hours of continued darkness to change color.  They also like bright daylight which will keep the colors vibrant.   The actual flowers are small and yellow and grouped in the center of the bracts.  They are called cyathia.

As the days get longer and the nights shorter, the Poinsettia will lose it's vibrant colors and turn green altogether.  To keep your Poinsettia healthy, allow the water to drain completely from the pot as it will not tolerate sitting in water.  In fact, if it is allowed to sit in water, it will probably die rather quickly.  As a rule, we generally recommend to water lightly and allow to dry a bit between waterings when indoors as they generally require less water indoors than they would outdoors.  You can search indoor gardening tips on this blog as it relates to watering, feeding, lighting, etc. 

The Poinsettia can be placed outdoors during the warmer months, where morning sun and afternoon shade are available. Keep it in its pot so you can bring it back in when it starts getting cooler.  Temperatures of about 70 degrees are good.  Higher temperatures tend to shorten the life of the plant.  In May, you can actually pinch back the plant.  This is a process whereby the tips of the plant are removed down to the next set of leaves.  By doing this, you remove the natural growth hormone from the tips of the plant and force the plant to develop side-shoots or more branching.  This will keep the plant full and lush, along with the use of a good fertilizer during the warmer months.

Getting the  plant to come back into flower the next winter can be difficult as it requires 12 continuous hours of darkness for about 2 months beginning in Autumn when the nights grow shorter.  Any stray light during those 12 hours will interrupt the flowering process and make it more difficult.

It is rumoured that  Poinsettias are poisonous, and it is just that, a rumour.  There is a white latex material, or sap, in the stem and leaves that can cause  mild irritation to the skin and stomach, but it is not poisonous.  If ingested, it can cause diarrhea and vomiting.  Of course, if one is allergic to the plant or latex, one could suffer a severe allergic reaction.

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