The Light Types for Growing Orchids

Incandescent Lights

• Incandescent lights are the most common type of light found in most homes. They produce a lot of red light and some infrared light, but very little blue light. Plants need both red and blue light to perform photosynthesis. Blue light is also needed for leaf growth, while red light helps stimulate flowering and affects maturation. Infrared light also plays an important role in flowering. If you’re growing your orchids under incandescent lights, make sure you keep the lights at least 2 feet away from your plant to avoid burning the leaves. Incandescent lights generate a lot of heat. In order to provide your flowers with enough blue light, you will probably have to use some fluorescent lighting.

Fluorescent Lights

• Fluorescent lights produce a cool white light that doesn’t burn plants. They’re economical, and the bulbs usually only need to be replaced every couple of years. However, many fluorescent lights are low-watt lights that won’t give off enough light to satisfy even low-light orchids. Fluorescent lights produce a lot of blue light, but many don't emit much red light. Some fluorescent lights are wide spectrum lights that emit both red and blue light.

High-Intensity Lamps

• High-intensity lamps require special lighting fixtures that can deal with the power requirements of these lamps, which range from 100 to 1,000 watts. High-intensity discharge bulbs are expensive to replace, cost between $35 and $100 each, and usually last around two years. These lights are designed specifically for growing plants that require intense light, and they’re very efficient, but they produce a lot of heat. The two most common types of high-intensity lamps are high-pressure sodium and metal halide. You can grow orchids under either type, but they will do better with the metal halide bulb because it provides a wider spectrum of light.

Intensity

• Light intensity is measured in foot-candles (fc). One foot-candle is the amount of light produced by one candle at a distance of one foot. The outdoor light level on a bright summer day is more than 10,000 fc. Low-light orchids such as Masdevallia, Miniatures, Paphiopedilum and Phalaenopsis need 1,000 to 1,500 fc of light. Grow them on the windowsill of an east window, within one foot of a west windowsill, or within two feet of a south windowsill. Moderate-light orchids like Miltonia and Zygopetalum need 1,500 to 3,000 fc and can be grown on the windowsill of a west window or within 1 foot of a south windowsill. High-light orchids like Cattleya, Cymbidium, Dendrobium and Vanda need 3,000 to 4,500 fc. Grow them on a south windowsill or within 1 foot of a south windowsill, but make sure they don’t receive any direct sun in the middle part of the day.