Where there’s a will, there’s a way. You can still grow orchids under artificial plant light even if natural sunlight is insufficient or unavailable. Orchids grown indoors under good artificial light can be just as healthy as the ones grown in natural light. However, it is not as easy as putting your orchids close to a light bulb. Having a basic understanding of plant lights and your orchids’ light requirements will greatly enhance your success.
Intensity
One great thing about growing orchids under plant lights is that the light intensity does not need to be as high. The reason is that artificial plant light is very uniform. No matter how rainy or cloudy outside, or how short the winter day, your plant light is available as soon as you (or your timer) turn it on. Moreover, reflectors and reflecting surfaces make the available light more efficient, as well as allow the light to reach the underside of the leaves. Furthermore, you can expose your orchids to longer hours of light to compensate for the lesser intensity. Generally speaking, you can provide 10% to 20% less light to your orchids when grown under plant lights. Check out my Orchid Light page to understand the light intensity requirements of different orchids.
The farther away from the light source, the less intense the light is. Also, for standard fluorescent light, the middle of the tube emits more intense light than the ends. So try to put your plants in the middle if possible.
Duration
Some growers like to imitate nature and turn their artificial plant lights on when the sun rises and off when the sunsets. But others like to extend the daylight to accelerate growth. My recommendation is to have your lights on for 14 to 16 hours in the summer and 12 to 14 hours in the winter. I don’t recommend providing more than 16 hours of light because the darkness is as important as light to your orchids’ health. Some orchids are day-length sensitive as it is a signal for them to determine the time to bloom. For example, the famous Cattleya labiata sets buds in the fall when the day length shortens. Oncidium and Miltonia are also sensitive to day lengths. So for those orchids, you should gradually decrease the duration of light in the fall and winter.
Color
You might have learned in elementary school that the green pigment in leaves, Chlorophyll, absorbs light to produce food for plant growth. Chlorophyll absorbs the blue and red wavelengths of light and reflects the green (hence the green color). Therefore, even though natural sunlight contains many colors, only blue and red are used by plants. Blue light sometimes referred to as “cool” light, is primarily responsible for leaf growth while red light, sometimes called “warm” light, promotes flowering and fruiting. The good proportion is to have about one part of red light to three parts of blue light. This is important knowledge to have when you choose the right artificial plant lights for your orchids because different light sources emit different colors.
Types of Artificial Plant Lights
Manufacturers seem to be coming up with new types of artificial lights every other month, but don’t let that confuse or intimidate you. Essentially, I like to think that there are four common types of artificial lights for plants. They are:
- Incandescent light
- Fluorescent light
- Metal halide light
- High-pressure sodium light
Here is a table to do a quick and dirty comparison of the different lights for your orchids:
| Incandescent | Fluorescent | Metal Halide | High-Pressure Sodium | |
| Light color | Red/Warm | Both Red/Warm and Blue/Cool are available | Both Red/Warm and Blue/Cool are available | Red/Warm |
| Heat Emission | Very high heat | Low heat output | Medium low heat output | High heat output |
| Bulb Lifespan | 750 hours | 10,000 to 20,000 hours | 10,000 to 20,000 hours | 24,000 hours |
| Replace Bulb After | 3 to 5 months | 8 to 24 months | <250 Watt: 6 months>400 Watt: 1 year | All: 2 yearsSon/Agro: 1 year |
| Light Intensity | Low | Low to medium | Very High | Extremely High |
| Lumens per Watt (1 lumen in 1 foot = 1 foot-candle) | Up to 20 lumen | 45 to 90 lumen | 80 to 125 lumen | 100 to 150 lumen |
| Typical Bulb Wattage | 15 to 150 Watt | 20 and 100 Watt | 50 to 1000 Watt | 35 to 1000 Watt |
| Cost of bulbs | $ | $$$ | $$$$$ | $$$$$ |
| Cost of fixture | $ | $ (compact) to $$$$ (high-output) | $$$$$ | $$$$$ |