Regional Gardening Reports :: National Gardening Association

In the Garden:
Upper South
November, 2011
Regional Report

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An assortment of houseplants is sure to brighten the winter days ahead.

Houseplants: Winter's Antidote

Leaves are falling, the last tomatoes are ripening on the windowsill, and long johns are coming out of storage. I enjoy that there are four distinct seasons where I live, and the respite from outdoor chores is welcome at a certain level. Still, the need to be surrounded by something green and growing is strong. Without houseplants, winter's gray days would be unbearable. My collection runs the gamut from the rare and unusual to the common and ordinary, but they all bring pleasure. Whatever houseplants fits your own personality, home design, and budget, I encourage you to include some in your home this winter. Tending plants indoors this winter may not be quite as effective as those special lights for Seasonal Affective Disorder, but they will brighten your days in their own particular way.

As with any type of gardening, successfully growing houseplants hinges on choosing the right plant for the right place and meeting the necessary growing requirements. Light, soil, water, humidity, fertilizer, temperature, and pest control are just as important indoors as out.

Determining how much light your home affords is as much art as science. Yes, you can purchase a light meter to determine the number of foot candles, but often plants will defy the odds of survival. A good, and logical, rule of thumb is to consider which direction your windows are facing. Those windows with an unobstructed southern exposure will provide the highest light levels. This area is best for those plants needing the most light, such as citrus, herbs, and many flowering plants. East- and west-facing windows provide somewhat less light, but this will be adequate for a wide range of plants. A northern exposure gets the least amount of light, but this situation generally proves adequate for those plants with large leaves. These include the most common, and easily grown, houseplants, such as aspidistra, dieffenbachia, philodendron, and schefflera.

If the natural daylight does not seem adequate for houseplants or if you want to brighten an area of your home for both you and plants, then some type of artificial light is the best choice. The cheap solution is a 2-foot or 4-foot fluorescent utility fixture fitted with both cool-white and warm-white bulbs. Beyond that, there is an ever-increasing number of solutions, include special grow-light bulbs, smaller diameter fluorescent bulbs that use less energy, high-wattage "spotlight" fluorescent bulbs and fixtures, plus specially designed LED and halogen lights for growing plants. This is a maze where one can easily get lost. Try to made do with the natural light you have available, choose a simple light fixture, or be ready to do major research.

Hopefully, everyone has already heard the mantra, "Use the best quality soilless potting mix you can buy." How do you know which ones these are? Talking with people at local independent garden centers is your best bet, as what is available varies from area to area. One recommendation I've recently read is to choose a mixture labeled for African violets. Unfortunately, most soilless potting mixes are based on peat moss, which invites environmental concerns. One solution is to mix your own, using four parts of coir, made from shredded coconut hulls, to one part perlite, made by heating naturally occurring volcanic glass.

If you succumb to purchasing the ever more widely available phaleanopsis orchids, consider purchasing a potting mixture with long-fiber sphagnum moss, pine bark, cork nuggets, expanded clay aggregate, and perlite. My orchids have been thriving in this, even sad-looking ones I've purchased at deep discount and repotted when they came home with me.

When potting or repotting houseplants, first and foremost, use a pot with a drainage hole in the bottom. Next, avoid the old notion of using shards of broken clay pots in the bottom to cover the drainage hole. Instead, cut a piece of window screen to fit into the bottom of the pot. This will keep the soil from washing out or clogging the drainage hole.

There is no hard-and-fast rule to watering houseplants short of touching the soil to determine if it is dry. The type of heat source, the weather, how root bound the plants are, and the type of potting soil all affect how often watering is needed. In general, I break the rules by letting the soil get fairly dry before watering, then letting the plants sit in the water in the saucer. With experience, I've learned which plants tolerate this treatment and which ones don't, then adjust accordingly.

Humidity, Air Circulation, and Temperature
Most of our homes in the winter have very dry air, while most houseplants, excluding cacti, are from humid rain forests. A whole house humidifier system will benefit both you and the plants. If most of your plants are growing in a single room, consider adding a room-size humidifier. Actually, grouping plants together will usually raise humidity levels enough for them to grow adequately. Placing them on pebble-filled trays is even better.

An often overlooked aspect to growing healthy houseplants is air circulation. Try adding a small fan or a ceiling fan, with either one set on low. You're going for a gentle breeze, not a wind storm.

Most houseplants fit into an ecologically minded home with the thermostat set to the mid- to high 60s during the day and slightly lower temperatures at night.

The official recommendation is to not fertilize houseplants during the winter as they are not actively growing. Since I have fairly bright light where my houseplants spend the winter, I feed all winter using a water-soluble houseplant fertilizer with every watering. The one rule I do follow is to choose a fertilizer that does not use urea as a nitrogen source as I've read that it is not good for African violets (all my houseplants get the same fertilizer except for the orchids). Have I done a comparison study? No, and I'm open to your input.

No matter how carefully you've inspected your plants before bringing them home, you will end up with pests, usually in the form of mealybugs, scale, whiteflies, or spider mites. There is no easy, simple fix. Keeping your plants healthy with adequate light, water, humidity, and fertilizer is the first line of defense. Next, try insecticidal soap. For mealybugs and scale, use an artist's paintbrush or cotton swab dipped in rubbing alcohol. Constant vigilance is imperative.

Most likely, you already have some houseplants. Enjoy them this winter, and consider adding some more. They'll reward you with in many ways as you await those first warm days of spring.

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