Originally Published In The Deseret News Wednesday, January 15, 1992
- Larry A. Sagers Is A Horticulturist With The Utah State University Extension Service.
Indoor gardening provides a way of enjoying plants through the cold and dismal weather. There is really no such thing as an indoor plant, only plants that have been moved indoors. All plants have a native outdoor environment. We have moved them from those environments to our homes and force them to adapt to our living conditions. This adaptation may or may not be successful.
Indoor plants are native to diverse environments. These include arctic woodlands, tropical rain forests and burning deserts. In spite of the vast difference in their native environments, we often lump plants together in the home and then wonder why they don't do well.
All plants have certain basic requirements to sustain life. These include adequate light, temperatures and the right amount of water in the soil and in the air. Plants also require a growing medium for the roots. This growing medium must provide support to the plant as well as dissolved minerals and moisture necessary for the plant to survive.
Light, in my opinion, is one of the most critical essentials for the growth of green plants. Green plants use light to convert water and carbon dioxide into food. This photosynthesis process feeds the plants and also ultimately feeds all of us. Plants only manufacture food when light is present, but they burn food both day and night. If a plant does not get enough light, it uses stored energy and then starts consuming itself. Insufficient light results in weak, stunted and spindly growth with thin pale stems and small leaves that turn yellow and drop. Plants with sufficient light use relatively larger amounts of fertilizer and water and can adjust to a wider range of temperatures.
Light intensity is often measured in foot candles. This measurement is the amount of light in a totally dark room produced by one candle on a square foot of surface 1 foot away. It is roughly equivalent to the amount of light produced on a piece of paper by an evenly burning match 4 inches away. Most of us lack a way to measure light. An easy way to test sunlight intensity is to hold a sheet of white paper in the area where you want to grow a plant. Hold your hand a foot above the sheet and observe the shadow. If there is a sharp, well-defined shadow, that indicates you have bright light. If you have a fuzzy, but recognizable shadow, you have filtered light. If you see only a blur, then most plants are not going to like that area without the addition of some kind of light. Most good houseplant books give the amount of light needed for certain plants to do well.
One common problem in our area during the winter is a greatly reduced light intensity. Shorter days, haze and clouds cause many plants to literally starve during the winter. Help plants adjust to this lower light intensity by reducing watering to just enough to keep the plant from wilting. With no light it is impossible for the plant to grow. Don't give it confusing signals. Fertilizing when a plant is not growing makes little sense as it signals the plant to begin an active growth process when light for growth is not present.
Improve the lighting of plants by moving them to a different area. Plants growing away from windows should be rotated every three to four weeks to an area near the window. This allows them to recharge their stored energy so that they will have food to live on when moved back into a darker area.
Washing the windows in the middle of the winter may not be a favorite task, but dirty windows can cut the light intensity by as much as 40 percent. Because our eyes adjust readily to decreased light levels, we don't notice the problem, but the plants certainly do. Increase light reflection by using white backdrops, aluminum foil or other reflective surfaces. You can also increase the light by adding artificial light. Artificial lights, however, must be located very near the plant (6 to 8 inches) to produce much effect. Longer periods of weaker light have roughly the same effect as the shorter period of strong light.
Occasionally, too much light is a problem. With the high light intensity on our infrequent, but enjoyable, clear days, plants in a south window may get too much light. Sheer curtains or blinds can block the light temporarily and prevent sunburning. Too much light causes leaves to turn gray and become bleached or scorched. Tender plants may even shrivel, wilt or die. Plants can adapt to higher light intensities, but those that have been grown in very low light intensities are often badly damaged by sudden exposure to strong sunlight.
Adding more light to your plants is one of the best treatments during periods of low light or cloudy weather or when the plant is not doing well. Plants usually go through resting phase during the winter when light is limiting. They require less water during this time. Next week we will discuss more about growing plants indoors and how to control some of the pests that are likely to invade your indoor garden.
© 1998 Deseret News Publishing Co.
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