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Saturday, January 05, 2002

By Curt Pesanka and Marjorie Radebaugh, Phipps Conservatory and Botanical Gardens

It was early October and we had just finished installing the Garden Railroad exhibit when we noticed an excessive amount of leaves falling from one of our large ficus trees.

Ficus trees react to changes in light or temperature by shedding their leaves. Natural light levels had decreased steadily as we headed toward November. We added artificial lighting to supplement the available light and within weeks, the tree was back to normal.

	Growing with Phipps Previous articles in a series Hardscaping provides garden framework This is one of a series of periodic columns by staff members of Phipps Conservatory and Botanical Gardens. Curt Pesanka is the foreman of the horticulture department, and Marjorie Radebaugh is the head of education.

Reduced natural light in a home during the winter may cause the same symptoms. Without sufficient light, plants cannot carry out enough photosynthesis to produce the food necessary to create new leaves, roots, stems and flowers. By spring, the plants may be weakened and become unattractive and leggy. Their weakened condition makes them more susceptible to insect and disease problems. The addition of artificial lighting can help to maintain healthy plants throughout the winter season. Artificial lights can also be used throughout the year in areas of your home that never receive much natural light.

Incandescent bulbs, commonly used in lamps in our homes, can supplement existing light over winter. Incandescent plant spotlights may also nicely highlight plants. However, incandescents are not the best choice; they provide light mostly in the red and far-red range, and if they are used as a primary light source, leggy plants may result. They are also inefficient, giving off a lot of heat that can burn plants if they are placed closer than 12 inches from the light.

Fluorescent lights are excellent for growing plants 20 inches tall or less. African violets, small cactus and tropical plants and seedlings are examples. The lights should be placed 2 to 12 inches from the top of the plants. Be careful not to place these lights too far away from the tops of the plants or they will not be effective. Plants placed 12 inches from a light receive twice as much light as those that are 24 inches away.

Fluorescent tubes are available in sizes from 8 to 96 inches long, with 48 inches being the most commonly used and the most practical. Ready-made fixtures are available that hold one to four parallel tubes. Most tubes should be replaced after one year of use, because they gradually decrease in light output over time. Two 4-foot tubes can be used to cover an area that is 4 feet by 1 foot wide.

A number of different types of fluorescent tubes can be used. Cool white tubes are widely available and are fine for growing most plants as well as lighting homes and businesses. "Plant" tubes primarily give off light in the red and blue range, which plants use most. They may produce slightly more growth than cool white tubes, but for the extra cost involved, they are probably not worth it.

Wide-spectrum grow lights are good for plants that need extra amounts of sunlight or are about to flower. Verilux tubes come closer to natural light than most other tubes and produce excellent growth and bloom, with plants and flowers shown in their true colors. (These same tubes are often used in light therapy, reducing the winter blues that some people experience as a result of lower winter light levels.) The tubes, although more expensive than ordinary fluorescent tubes, may last as long as four years. Verilux tubes are available at some True Value hardware stores and other retailers or through the Healthy Lighting catalog, 888-544-4865, Ext. 112. or /.For taller plants, the Wonderlite produces intense, natural-looking light. It is screwed into a ceramic incandescent fixture and can be recessed into the ceiling or put into a track. Strong enough to be effective at a distance, it won't burn foliage placed 2 feet or more away. This combination incandescent/mercury vapor/fluorescent light will produce growth, not just survival. These lights are guaranteed for one year but usually last three. The 160- or 300-watt lights can be ordered from Public Service Lamp Corp./Westron by calling 1-800-221-4289.

Brighten up your home this winter with supplemental lights and you're sure to be pleased with the results.