Getting your plant home safe and sound is the first big issue. Don't buy a poinsettia and leave it in your car while you go and do more shopping. The poinsettia is a cold-sensitive tropical plant.
It will be irreparably damaged by exposure to cool temperatures. Take it from the store into your warm car and straight into your home.
Watering is the next big issue. Don't overwater. This kills more poinsettias than cold damage. Wait until the leaves of the plant droop a little before watering.
Stand the plant in a sink of shallow water, which allows the roots to take up what water it needs, and give it a cup of water under the leaf canopy. Use lukewarm water, not cold water, to avoid shocking the plant. They use lukewarm water in the greenhouses when they water. You should do the same.
Don't leave the plastic cover on. Air circulation is important. Plants that look twiggy and have a lot of leaves falling off have probably been exposed to cold or left in their plastic sleeve too long.
Sniff the plant before buying. If the roots are rotting from over-watering or poor air circulation, there will be a sweet, musty smell. This is a sign that the plant is already on the decline.
Enjoy them for the season, then ditch them and move on. It takes extraordinary effort to get a poinsettia through the year and to colour up again. It's not worth your time and effort.
There are two common misunderstandings about the poinsettia.
One is that the red leaves are actually the plant's flowers. They aren't. They are bracts that change colour as the daylight starts to diminish in the fall.
The plant's true flowers are scentless, yellow and inconspicuous, and can be found tucked among the leaves in the centre of the plant.
The other error is that the plant is deadly poisonous, especially to pets and young children who might eat the leaves.
This scare started in 1919 with a story that a two-year-old child had died from eating poinsettia leaves. It never happened. It was pure urban myth.
Researchers have since shown that it would take a child weighing 50 pounds to eat at least 500 poinsettia leaves to reach a potentially toxic dose.
As with many plants, there is a degree of toxicity with poinsettia leaves, but people and pets are not likely to eat any of them as the taste is repulsive.