Good gardening friend Paul Parent of the Paul Parent Garden Club (http://www.paulparent.com/) sends out a great newsletter every week with pertinent gardening topics. I encourage you to go to his website to sign up for his newsletter. Paul can also be heard every Sunday morning from 6 AM to 10 AM at his website or at WBACH (104.7 FM) every Sunday morning from 6 AM to 9 AM. Paul recently sent this article out called "Keeping Houseplants Healthy in Winter" (I occasionally add a few comments in italics) and here it is:
Keeping your houseplants healthy during winter months may seem difficult. Light from windows is reduced, days are shorter and humidity may be lower due to heating. But by making a few changes, you can help keep your houseplants healthy.
Keeping things light
In winter, your plants receive sunlight for less time and in less intensity. Houseplants native to rainforests that are used to lower light will be fine with that, but most plants need more light. Try to move your plants near a brighter window (S/SW exposure) to get them more sunlight.
If you have no brighter windows (due to shade trees or apartment living), you might want to consider the purchase of plant lamps that are designed to provide the full spectrum light your plants need. They can be mounted under shelves, over plants or on specially-designed plant stands. Leave them on about eight hours a day, and they'll give your plants the light they need. Consider using the newer LED lamps. They are a bit more expensive, but they use less energy and are more efficient for producing the part of the spectrum that is needed by plants. In short, you aren't wasting your energy (and money) producing excess heat or light in spectra that your plants don't need.
Most plants do not do well when subjected to rapid fluctuations in temperature. Keep them away from hot air sources and cold drafts alike. Run ceiling fans on low if the house is closed up. Fans break up stagnant air; that's healthier for both you and your plants.
Some symptoms of low humidity are brown leaf tips and wilting. Low humidity makes your plants work harder to get moisture from the air and soil, as well as keep what they have inside.
One way to give your plants some extra humidity is to put a layer of pebbles in the bottom of a tray and fill the tray with just enough water to cover the bottom of the tray (below the top of the pebbles). Place potted plants in the tray. (Refill the pebbles with water as needed)
Fertilizing should be done less often for most plants in winter. (I often recommend all natural "Dynamite" fertilizer granules that you can put down every 3 months of the year. This gives your plant a gentle dose of all natural nutrients--great for your soil!)
Give your plants a good washing. Dirt, dust, grease, and other particles can settle on leaves. Dirty leaves can't absorb as much sunlight as clean ones. Gently wipe clean the leaves with a soft sponge or cloth dipped in plain tepid water. Sturdier plants can even be given a quick shower in the bathroom with tepid water. (This is awesome advice. Even in the best of homes our plants get dusty and mites and other insects LOVE to make their homes in that dust. Give the "bad bugs" less of a chance!)