Houseplants May Need A Light Boost

Sunshine. Oh, how we enjoy it. It’s great for our spirits and brightens our dispositions. But what we use as a stimulus for a day in the garden or a round of golf, our plants use for various growth activities - germination, flowering and manufacturing food.

Unfortunately, our winters of low light and bleak days do very little for the disposition and overall health of our houseplants. A good shot in the stem of a few hours of bright sunshine every day would be what the plant doctor would order. But there is only one way of achieving that needed light for our houseplants and that’s through the use of artificial lighting.

Before we go about setting up banks of lights, we need to understand what makes our little plants tick. As schoolchildren, we learned about photosynthesis. Since, for some, this may have been many moons ago, here is a little refresher course:

Quite simply, it’s the process by which a green plant is able to make carbohydrates from water and carbon dioxide, using sunlight as an energy source and chlorophyll as the catalyst.

Sunlight is made up of a spectrum of colors. The blue and red are the most important colors in the photosynthesis process. The cool blue stimulates plant growth and keeps the plant compact, while the warm red simulates flowering.

The long, white fluorescent tubes often used as office lighting, are excellent sources of both the red and blue wavelengths. However, when you go to purchase them, you may find yourself a bit confused. Fluorescent lights are sold as warm white (emitting red wavelengths) and cool white (emitting the blue wavelength).

The cool whites are the most readily available. The warm whites can usually be found at local lighting stores. Since the color variations between red and blue lighting are rather small, plants can be grown under either. They will do much better, however, if grown under both.

One other note on fluorescent lighting - in order for fluorescents to work efficiently, they must be only three to four inches above the plants. The best use for fluorescents is germinating seed or over small plants such as African violets and orchids. They also work fine for holding over summer annuals such as geraniums or fuchsias.

I am asked often about the use of incandescent lights (the common lightbulb). Incandescents burn very hot and give off red wavelengths.

In order for the plant to benefit from the light, it has to be very close to it. The heat from the lightbulb could easily burn the plant. Manufacturers have produced special incandescent grow lights that give off both the red and blue wavelengths, yet, they, too, burn hot.

The High-Intensity Discharge Lamps are excellent sources of light, but some can be dangerous. Depending upon the light, they can burn eyes and skin. Some, if not handled correctly, can explode. Learn all you can about these lights before purchasing them and always handle them with care. Tanning lights can never be used around plants. The ultraviolet radiation as well as excessively hot infrared rays can damage plants.

The intensity of light and whether that light is red or blue aren’t the only considerations. We need to know how long to keep the lights on. This is determined by the plant’s day-length requirements - the length of time a plant needs to be exposed to light in a 24-hour period.

Short days have 13 to 14 hours of darkness and 10 hours of daylight. Fall- and winter-blooming plants such as poinsettia and Christmas cactus usually produce buds during this time. Long days have about 10 hours of darkness and 13 to 14 hours of daylight. Summer flowers bloom during this time. Day-neutral plants are just that, neutral. They don’t care if the days are long or short. Most geraniums, tomatoes and African violets fall into this category. They set buds when they reach a certain age and size.

Once the light requirements are determined for a specific plant, simply leave the lights on for the necessary time. The only problem may be conscientious caretakers who want to save electricity and faithfully turns off their bank of lights on their schedule, not the plant’s. If lights need to be left on for 14 hours, then leave them on for 14 hours. There are inexpensive timers that can be purchased to ensure the lights go on and off at the proper time. With a little imagination and the help of supplemental lighting, houseplants can grow to be healthy old specimens in just about any crook or cranny of the house.