During the winter, most houseplants need less water and little if any fertilizer because their growth has slowed down. They are not in an active growth phase because of short days, reduced humidity and lower temperatures (unless you are growing them in a greenhouse).
The amount of water needed depends on the plant species, but most prefer to be watered when the potting medium is barely moist to the touch or almost dry. Ferns prefer to be kept more evenly moist, while succulents do best if allowed to dry out more between watering.
When you do water houseplants, water them thoroughly. Water should freely drain out of the holes in the bottoms of the pots. If the excess water collects in a saucer, empty the water and replace the saucer beneath the pot.
Most houseplants will perform well in winter with daytime temperatures of 65 to 75 degrees and night temperatures of 60 to 65 degrees in winter. Temperatures below 50 degrees or rapid temperature fluctuations may damage some plants. Keep houseplants away from cold drafts, radiators and hot air vents, and make sure houseplant foliage doesn't touch cold windows.
Houseplants with large leaves and smooth foliage, such as philodendrons, dracaenas and rubber plants, can benefit if their leaves are washed occasionally to remove dust and grime. Cleaning houseplants improves their appearance, stimulates growth and may help control insects and mites. Large, firm-leafed plants may be cleaned with a soft sponge or cloth and tepid water. Another method is to spray off the leaves in the shower. Do not use leaf polish, which can clog tiny pores in the leaves.
Holiday gift plants often have their pots covered in decorative foil that traps water around the roots of the plants. Remove the foil from the bottom of the pot or punch holes in it to allow water to drain properly. Place the pot in a saucer to protect wood surfaces from the standing water and condensation that can build up beneath it.
Poinsettias like lots of bright, indirect sunlight. They are sensitive to extreme temperatures so it is best to keep them away from cold drafts and heat vents.
Daytime temperatures of 65 degrees are best to prolong the display of the colored bracts. Water the plants thoroughly when the soil is dry to the touch. There is no need to fertilize them during the holiday season.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.