Here are thumbnail hints on caring for poinsettias, whether you buy them before Thanksgiving or before Christmas:

ARRIVING HOME. Get a fresh start by watering the plant from the top, letting it drain for 5 to 10 minutes, then choose a location for the plant to spend the holidays. Use warm tap water.

LIGHT. Poinsettias don’t need full, direct sun, only bright indirect sunlight near a south-facing window. If need be, adjust curtains and blinds to allow sunlight to enter the room. Beware of heat sources like heat registers and radiators. Poinsettias will not survive for very long if they are placed near heat sources or drafts. If you must locate the plant near a heat register, use a plastic heat deflector on the register to direct hot air away from the plant.

TEMPERATURE. Poinsettias need to be warm during the day, not hot, and with cooler temperatures at night. Pick the room based on the plant’s needs. Daytime temperatures should be between 65 and 70, but no higher. Room temperatures above 70 will play havoc with the colored leaves (bracts). Before you retire at night, move the poinsettia to the floor (away from heat registers, etc.) where overnight temperatures will range between 55 and 65 degrees.

HUMIDITY. By their very nature, poinsettias are semi-tropical plants, so they must have acceptable humidity in the home to hold onto its colorful bracts. Some homes have humidifiers built into their home heating systems, in which case there should be sufficient humidity for poinsettias displayed in the home. Otherwise, plan on “double-potting” your poinsettias. Picture the coffee cup-and-saucer. The coffee cup is your potted plant, the saucer is a wide tray under the plant. Ideally, the “tray” should be as wide as the poinsettia. In the center of the tray, turn a small bowl upside-down to provide a pedestal for the plant. Inside the tray, set down an inch of pebbles or colored stones from the nursery. Add water so it is just below the tops of the stones. Water vaporizing from the tray will provide a constant humidity around 30 percent to provide a tropical environment for the poinsettia. Check the water level in the tray regularly so it doesn’t run dry.

WATERING. To know when to water (tepid water, that is), rest a finger on top of the soil. If you sense moisture, do nothing, but check the next morning. When your finger senses the soil starting to dry, immediately add tepid water from the top of the pot, enough so it drains from the base of the pot. Do this in the sink at all times. Only morning watering should be done, thereby allowing the soil to dry somewhat during the day before the plant enters nightfall.

FERTILIZING. Although commercial growers provided constant fertilization for your plant before it was delivered, we don’t want to omit plant food entirely before and after the holidays. Some food is better than no food. Use a good quality liquid plant food you probably have on hand. Check the label, then use one-third the label rate to pre-mix a quart of fertilizer in an empty plastic gallon milk jug. Label the jog so you know it’s poinsettia plant food. Keep the jug away from young children and grand-children. Every two weeks in place of your regular watering, use a 50-50 mix of warm water and your poinsettia plant food. Keep a memo pad of the dates so you know when you fertilize the next time.