It's Not Easy Being a Houseplant in WInter 

Central heating creates dry air, so misting houseplants daily improves their environment.

Keep houseplants away from cold windows.

A geranium elongates towards the window as it searches for light.

Generally houseplants are tender tropicals that hail from warmer climates. Even aspidistra, peace lilies and other low light houseplants thrive outside in USDA zones of 10 and above. When grown as houseplants they enjoy vacationing outside during the summer, but as soon as temperatures cool and the sunlight hours lessen, they decline. That's why they should be brought inside before the weather turns.

Once they are brought inside they show their displeasure with yellow foliage, premature leaf drop and brown leaves. But it's not just vacationing tropicals that suffer during the winter, African violets and other houseplants that didn't even venture to the outdoors can lose their lust for life. 

Central heating, dry air, lack of daylight hours, weak light combined with cold windows and drafts, inadequate water, too much water, using water that's too cold - all make life difficult for plants during the winter.

To help plants through survive the winter, and all year round they would appreciate:

• to keep them away from cold windows, drafty doors and heating vents.
• misting at least daily and/or group them together as this increases the humidity.
• supplemental lighting.
• to ease up on the watering during the winter, but don't allow the soil to dry out too much. 
• watering with room temperature water or warmer, not cold.​

Even in January, this geranium is stocky and healthy due to supplemental lighting.

My stock of overwintering geraniums.

Bringing in Tropicals & Houseplants from their Vacation: Inspect geraniums, bougainvilleas and other plants that were brought in from outside. Remove spent, diseased plant parts and debris from the top of the soil. Watch for slugs and snails on top of the soil and hiding on containers. For more on overwintering geraniums, bougainvilleas and other tropical plants click here. ​

Supplemental lighting is necessary to keep plants healthy and vigorous over the dark winter months.

Palms and other tropical plants thrive in an atrium.

​More Light Please: Winter daylight is inadequate for houseplants and overwintering tropicals; it’s just too weak and doesn’t last long enough. Even when they are moved to a south facing window, their foliage becomes pale, stems elongate and stretch towards any available light. Indoor plants benefit greatly from supplemental lighting either fluorescent or grow lights. Whatever type you use, put them on a timer so they are on for 8 to 12 hours per day.
 
Fertilizing & Repotting
Plants are not actively growing now so they require less water and generally don’t need to be fed. Overwatering is often the number one reason houseplants die. Check the soil with your finger before watering and allow soil to dry slightly. On the other hand, avoid keeping the soil too dry as this encourages spider mites.
Wait until spring to repot pot-bound plants when they actively start growing again. Roots tend to slow down and even may die-back during the winter. The only exception is if plants are top heavy and keep on falling over, then just replant in a pot just one size larger. 

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Kill mealybugs with a q-tip dipped in rubbing alcohol.

The mottled appearance of a spider mite infestation.

Insects
Inspect houseplants for insects when they appear sickly. Look for leaves that look pale, dusty and develop pale yellow spots. Check for tiny black bits under the leaves as they are the insect’s excrement. Look for tiny spider webs that cling to stems and leaves dotted with excrement. Examine under leaves, along stems, all nooks and crannies as well as the soil surface.  If you see eaten foliage and slime trails, check the plant, the soil, under the pot and drainage tray for snails and slugs. 
 
If insects are noted, sponge the plant down with a mild dishwashing liquid and lukewarm water. For small plants, just dip them upside down with your hand straddling the top of the pot. Keep them submerged for a few seconds then upright. It’s not necessary to rinse them. Another alternative, especially for big plants, is to squeeze a soapy sponge all over the plant. To kill any subsequent generations of insects, repeat every 7 to 10 days. ​For mealybugs, kill each individual insect with a q-tip dipped in rubbing alcohol. 

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Angel trumpets, Brugmansia, originates from Central & South America and is hardy in Zones 10 to 12. Prefers moist soil, prone to spider mites if too dry.

Devil's trumpet, thorn apple, Datura fastuosa 'Double Purple', are native to Mexico, South America, USDA 10 to 12. Prefers full sun and moist rich soils.

Flamingo flowers, Anthurium andraeanum, is a tropical native of Central & South America. Prefers warm temperatures and high humidity. It's grown outside in USDA 10b to 11.

A single flowered jimsonweed, Datura metal, like all daturas is poisonous.