During the winter months when the day-length is shortened and the sun intensity is very low, growing indoor houseplants becomes a whole, new way of life. It is almost never a good idea to keep houseplants real moist, but it is especially bad during the winter months. Too much moisture will surely cause root-rot, yellow leaves and mildew. It is best to remember a few simple rules…forget the old “water once a week” routine and only water when the plant is dry. That may be once a week, once every 12 days or maybe even once a month! Just do not water too often. You should always water thoroughly (as long as you have good drainage) but allow plenty of time between waterings.
No fertilizer during the winter months. Plants need lots of light, especially real sunshine in order to make use of any fertilizers that may be applied. If your plants are having problems such as leaves turning yellow and dropping off, applying fertilizer will not help. Remember that “fertilizer is food, not medicine.” If your plants need help, water with a fungicide rather than with a fertilizer. Fungicides may help stop the problems from spreading but it is helpful to know that fungus problems are easier to prevent than to cure. Therefore by knowing that winter darkness and too much moisture can cause fungus to develop, it is a good idea to apply fungicides monthly before a problem arises.
Air circulation is very crucial during the winter months while all of your doors and windows are tightly closed. I like to run one or more circulating fans in the rooms where there are plants growing. Get the kind that oscillates so as not to continuously hit your plants with a breeze that could cause excessive drying in one spot. The speed control should be set on low as a slight breeze is best. Running a ceiling fan at the same time aids in mixing the air, which also helps to keep the temperature steady throughout the room.
Now as for the temperatures…most homes run between 68 to 71 degrees during the day and maybe a little cooler at night. Most of your tropical plants actually prefer to have cooler temperatures at night, somewhere between to 55 and 60 degrees. Maybe a spare bedroom with the heating vents closed or simply by placing your plants closer to a sunny window (remember, we are talking about nighttime temperatures) where coolness seeps through the glass. It is probably a good idea not to allow the leaves to actually touch the glass, as they will freeze to the frost on the inside of your window.
Whenever a plant has a problem, people always want to re-pot it right away. Generally, re-potting is not the solution. Re-potting changes everything in the root area and puts the plant into “intensive-care”, or shock. For your newly re-potted plant to recover from the shock of re-potting, one should simply wait until spring to do the job. Spring, summer and early fall are the best times for re-potting most plants.
Insects can be a problem during the winter months as it seems as though the little devils always appear in the house under dry-air conditions, especially as we near spring. Spraying your plants occasionally with insecticides can be a very unpleasant ordeal as most insecticides have a really bad odor. Try spraying your plants with a mild solution of lemony dishwashing soap every four to six weeks. If the insect problem gets ahead of you, feel free to remove leaves and even branches of infected areas. Your plants will thank you for it.