How to keep houseplants healthy in winter

Whether houseplants are kept indoors year round or they are moved in and out with the seasons, winter can be a challenging time to keep them healthy and happy. The air is drier, the light is lower, and drafts are cold. Gardeners may even be so busy with holiday festivities they forget to care for them.

The benefits of houseplants have been touted for years. Studies have shown they may decrease the incidence of colds, headaches, coughs and sore throats and improve overall health. They also remove toxins from the air we breathe in our homes. Certainly houseplants are worth a little effort, don't you think?

Here are some tips to keep your houseplants thriving in winter.

The majority of houseplants prefer daytime temperatures around 70 degrees and cooler temperatures at night. Drafts, cold or hot, can be fatal so keep them away from fireplaces, radiators and drafty windows.

Cut back on watering. Most houseplants require less water in winter. Instead of watering on a set schedule, let the plants tell you when they need water. Moisture meters are available for purchase, but it is as easy as sticking your finger in the soil. If it is dry at an inch or two deep it is time to water.

Stop fertilizing. Houseplants grow very slowly in winter, if at all, and don't need any fertilizer. Allow them their natural growth cycle and be ready to start fertilizing again when you see new growth in early spring. Begin feeding at half strength to wake them up gently.

Give them as much light as possible. Because days are shorter and the sun shines lower in the sky, grow lights may be necessary for sun-loving houseplants. And even plants that tolerate low light will appreciate a spot in a south or west facing window (as long as the window isn't drafty and their leaves are not pressed up against it). Remember to turn pots every time you water so all sides of the plant get sun.

The edges of leaves turn brown on houseplants that are growing in an environment that is not humid enough. Misting used to be recommended, but you would have to mist plants several times every day to raise the humidity level sufficiently. Instead, group plants together and let them create their own humid environment as they release moisture when they "breathe." Or set pots on shallow trays filled with pebbles to keep the pot from sitting in the water. Or, better yet, buy a small humidifier and situate it near plants.

Give houseplants a bath in the winter. Dust collects on a houseplant's leaves just as it does on the furniture, inhibiting its ability to make use of light. With a moist paper towel or soft cloth, gently wipe the dust from leaves or put all your plants in the bathtub and give them a quick, gentle shower.

Wait to repot. If they weren't repotted when they were brought back inside, wait until spring. Remove any dead leaves and cut back leggy stems to keep plants more attractive and tidier. New growth will begin again in spring.

Keep an eye out for insect pests. They are much easier to control if they are found and treated early.

Aphids suck the juices from leaves. If the leaves on a plant feel sticky, you most likely have aphids. Whiteflies are little gnat-like insects that fly in swarms around the plant. Spider mites cause speckling on leaves and webbing on underside of leaves if their infestation is more serious. All these pests can be combated with insecticidal soap or horticultural oil.

• Diana Stoll is a horticulturist, garden writer and speaker. She blogs at gardenwithdiana.com.