Gardening Articles: Care :: Plant Care Techniques

Those Pest-y Houseplants

by Charlie Nardozzi


When the outdoor winter landscape turns drab in most areas of the country, it's nice to have lush, tropical houseplants growing indoors to brighten your mood. Keeping houseplants growing well in winter can be a challenge, especially in cold climates. Many of them have tropical bloodlines; most grow best in areas with warm temperatures and high humidity -- neither of which is in abundance indoors. When a houseplant is struggling in the wrong growing environment, other problems, such as pests, can take over. Insects can thrive on stressed plants, especially where there is a natural lack of predators. Not only are the pests harmful to your plants, the exudates from their feeding can cause damage to rugs, floors, and furniture.

Although there are numerous pesticides on the market to control houseplant pests, many gardeners are leery of spraying harmful chemicals indoors. Fortunately, there are ways to control the insects without resorting to harmful sprays. The first step is creating a "houseplant friendly" environment in your home.

Imitating the Humid Tropics

Most foliage houseplants prefer a warm, humid environment. While it's possible to heat your houseplant-filled room to the 70&deg to 80&deg F. range they like, the result will be a drier environment. As temperatures climb above 67&deg F, air humidity levels drop dramatically. Unless you have a humidifier to keep the humidity at the 40 to 50 percent range, it's better to keep the room on the cool side (60&deg to 70&deg F) in winter to keep the humidity higher. However, don't allow the temperature to go below 60&deg F since some houseplants, such as African violets and gardenias, may stop flowering and drop leaves.

Another way to increase humidity is to group houseplants together and place them on a tray filled with 1 to 2 inches of crushed stones. Keep water in the tray below the bottom of the pots. The water will evaporate and provide humidity.

Let There be Light

While many houseplants grow as understory plants in subtropical and tropical forests, they require more intense lighting in winter in our temperate climate. Plants not receiving enough light will produce tall, leggy growth and dull, pale leaves. Keep plants growing well by placing them near a sunny window or door, but away from cold drafts. Consider using full spectrum or halide lights to provide the light intensity and duration that plants need.

Watering and Washing

Periodically washing leaves to remove dust, and allowing some air (not cold air) movement around plants will improve plant growth and also reduce the number of insects that call your plants home. Tropicals grow more slowly during these darker months, so they need less water and can become stressed from overwatering, which causes brown leaf tips, leaf drop, and wilting. Plants also need less fertilizer because they are growing more slowly. Excess fertilizer causes succulent growth -- a magnet for aphids and other sucking insects.

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