A staple of Christmas-time is the Poinsettia. Contrary to legend, it is not a poisonous plant. Although it is often thrown away after Christmas, although Beth Paule of Season's Garden Center in Godfrey says it is possible to get many years of use out of the potted plant.
As for watering, she advises to take the plant out of its decorative pot cover when it feels dry, set it in the sink under the faucet until it is wet all the way through, and then put it back in the pot cover. She says to avoid letting it sit in water.