When it comes to lighting a greenhouse, nothing works better than natural light. Should you utilize your greenhouse to grow plants in sunlight, or if the construction or placement of the greenhouse limits the light that enters it, you may need supplementary light. Bear in mind that the wrong kind of light can stunt plant growth.
Not Enough Light
A common problem with greenhouse lighting isn’t enough light. If plants don’t get enough light, then they have a tendency to stretch, growing ever greater, seeking more light. Light-starved plants eventually become spindly and top-heavy. Energy that could go into leaves, flowers and fruit goes to stems, and the plant weakens consequently. Getting plants sufficient light entails making certain the artificial lights have a high enough wattage. It also involves ensuring that the light is close enough to the plant. For seedlings especially, the light should be only 1 to 2 inches from the bulb.
Too Much Light
Plants can get too much light. Throughout the afternoon, plants use water and light to make starches and oxygen. At nighttime, the plant converts these starches to sugars and stores them. Among the problems with greenhouse lighting is that it may be left on around the clock to spur fast development, but doing so compromises the health of plants. Plants given an excessive amount of light become pale, sometimes sunburned. A span of roughly eight hours of darkness each night helps plants preserve their wellness.
The Wrong Kind
Plants use mainly red and blue light for photosynthesis. High-pressure sodium lights put out most of their light from the yellow range, which is virtually unusable by plants. Incandescent lights put out broader range of light, but they put out heat, something that may damage little, tender plants. Metal halide and fluorescent tubes have been better options. They’re trendy and efficient and they put outside light the plants can utilize.
Uneven light means some plants will grow well while others languish. Though different plants have different light requirements, generally speaking, greenhouse lighting should provide 20 to 40 watts of light per square foot, spread evenly across the growing surface. That light must also have the ability to reach all the leaves. Plants that are spaced too closely will have some leaves that are shaded all the time.