Poinsettias require a constantly warm temperature between 16-18 degrees celsius.
Leaving a poinsettia outside for any length of time will kill it. Even leaving it inside your car or in your boot when the weather is freezing outside may result in its death or at the very least it will drop its leaves.
Position your Poinsettia away from draughts (away from external doors) and direct heat sources (away from radiators).
Watering
Check the watering every morning and only water when the soil feels dry to the touch.
If the plant requires watering, water thoroughly and then wait until the compost is moderately dry before watering again.
Ensure the water is tepid (at room temperature) and use a small watering can to ensure that you don’t overwater.
Poinsettias don’t like being waterlogged. If your poinsettia is in a decorative pot cover with no drainage holes ensure any excess water is removed after watering.
Sleeves
Leave the sleeve on the poinsettia until you get it home. This protects the plant from fluctuations of temperature and from damage.
Once you get the plant home remove the sleeve. You may find a couple of leaves have fallen off, or a couple have shriveled. You can remove the shrivelled leaves by gently pulling them downwards, they should easily snap away from the stem. Poinsettias extrude a milky sap when damaged, which can cause skin irritation to some people. If you are unsure wear gloves.