Houseplants' water, light needs change in winter

During the winter, most houseplants are not in active growing mode due to the short length of days, reduced humidity and lower temperatures - unless you are growing them in a greenhouse. Houseplants generally require less water and much less (if any) fertilizer because their growth slows down during the winter. Frequency of watering depends on plant species, but most prefer watering when the medium is barely moist or almost dry to the touch. Ferns prefer to be kept more evenly moist, while succulents prefer to dry out more between watering. Water houseplants thoroughly when you do water them. Water should freely drain out of the bottoms of the pots. If the excess water drains into a saucer, discard the water and replace the saucer beneath the pot.

It is a good idea to either remove decorative foil from the bottom of gift plant pots or punch holes in the foil to allow water to drain properly. Standing water and moisture that can build up under a pot without a saucer can damage wood furniture surfaces.

Most houseplants perform well with daytime temperatures of 65 to 75 degrees Fahrenheit 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. Also, 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 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.

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 work well for prolonging the display of the colored bracts. Water the plants thoroughly when 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.