Dr. Grow: Help your houseplants survive the winter

"At this time of the year, my houseplants do not grow well. What could be the problem?"

I hear this comment and question quite often. Outside of potential insect and disease problems, there are three things that you must take into consideration when growing plants in your home during the winter months:water, light, and fertilization.

When plants are confined to pots, proper watering is a must to maintain healthy plants. Some plants, such as poinsettias, like an evenly moist soil. You cannot allow the soil to dry out. Other plants such as pothos are more forgiving. I have actually failed to water a pothos for 30 days. When I did remember to water the plant, it perked right up and acted as if it were never forgotten.

In order to water a potted plant properly, use enough water to fill all of the pore spaces in the soil. You can either do this by watering from the top or from the bottom. Either way is OK just as long as enough water fills up all of the pore spaces. Excess water should be allowed to drain out of the pot. If you have a plant growing in a growers black plastic pot, which is placed inside a non-porous decorative pot, make sure that the excess water is removed from the decorative pot. Most plant roots will rot if allowed to sit in water for a long period of time.

The frequency of watering is extremely important. Use your finger to test the moisture level of the soil around your plant. If the soil feels dry, then it is time to water. If the soil feels wet, then don't water. I can't give you a formula that tells you how much water to use on Tuesday or Friday. Each home has different environmental conditions in it. The frequency of watering will depend upon types of heat, amount of light, presence or absence of drafts, etc. Use of the finger test will generally tell you when a plant needs watering.

Plants are designed to require different amounts of light to grow vigorously. For example a Boston fern requires high light levels to flourish. My wife, Marilyn, grows some absolutely awesome ferns outside in the shade during the summer. Just as soon as we bring them into the house during the fall, they begin to go downhill. Even though we place the ferns next to windows, the light intensity inside our home is not as high as the light intensity outside in the shade during the summer.

As fall marches into winter, light intensities decrease because the sun travels lower in the horizon. The region is also blessed with a lot of cloudy days during the winter. Both factors result in much lower light intensities. Plants used to high light levels during the summer just cannot make it on the lower intensities found during the winter. If you want to grow plants in your home, then you must choose plants that will grow under low light levels. A few examples are pothos, philodendron, dieffenbachia, Chinese evergreen, and peace lily.

The third requirement for plants to survive while growing in pots is proper fertilization. During the winter plants grow slowly and therefore require fewer nutrients. During the spring, summer and fall they grow more vigorously and you must continually replenish the required nutrients through fertilization.

For plants to survive, they must have 16 different nutrients. Hydrogen, oxygen, carbon come from water and air but the other 13 nutrients must come from soil. Since roots in potted plants are confined, the grower must replenish these nutrients on a routine basis.

The continual use of a common fertilizer such as 20-20-20 does not supply all of the nutrients required for plants to grow vigorously. You must also replenish all of the other secondary macronutrients and minor nutrients. These nutrients can be found in either fish emulsion or in a fertilizer prepared for hydroponic growers. Both of these products can be found at local garden centers.

If you keep in mind water, fertilizer, and light requirements you too can have healthy-looking and vigorously-growing houseplants adorning your home.

Paul Schnare of Cape Girardeau has been in the lawn and garden business for more than 20 years. He's an adjunct professor in horticulture at Southeast Missouri State University.