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Lighting Types

Don’t keep yourself (or your plants) in the dark!

Light is an essential component of photosynthesis, the process through which plants make their chemical energy. Plants use the same spectrum of light that humans see. While this light appears white, it is actually a mixture of all colors in the rainbow. Different pigments in plants absorb the various colors. The main pigment involved in photosynthesis is chlorophyll. Chlorophyll absorbs violet, blue and red light. It reflects green light, which is why plants appear green to us.

Photosynthesis does not require light from the sun - that is what makes indoor hydroponics possible. We are able to generate artificial light which can meet the needs of plants in terms of spectrum and intensity. The best artificial lights are called high intensity discharge lights, or HID lights.

There is no such thing as too much light for a plant, but most lights heat up the room they are in and should be turned off at least once a day. Most hydroponics gardeners provide their plants with between 10 and 16 hours of light each day. Lights should be hung about 30-36 inches above the plants.

High Intensity Discharge (HID)

HID lights provide a spectrum of light that is much closer to sunlight’s natural spectrum than fluorescent or incandescent lights. They produce light by making an electrical arc between tungsten electrodes inside a fused alumina or fused quartz tube. Inside the tube are gases and metals. The gases help the lamp start up, and the metals give off light when they are heated.

Initially, HID lights were quite expensive, terribly inefficient and only used by commercial hydroponics growers. However, they have improved a lot over the past few years and are now being purchased by many amateur hydroponics gardeners. They have reached the point where they are nearly as simple to use as any standard light bulb.

There are several different types of HID light, but only two of them are generally used for hydroponics purposes. These two lights are metal halide lamps and high pressure sodium lamps. Each of these HID lights produces a range of light that belongs to a different part of the spectrum.

HID lights are sold in wattages ranging from 250 to 1000, and sometimes even beyond. Most growers use a light in the range of 400 to 600 watts, but some prefer the power of the 1000 watt lights. A good rule of thumb is that you should use around 25 watts for every square foot of garden.


Which Type of HID Lamp Fits Your Needs?

Lights are the most expensive part of any hydroponics setup, so it’s important to choose the right ones. The most important thing to consider is what kind of plants are going to be grown. Metal halide lights make light from the blue end of the spectrum, which is best suited to immature plants and leafy greens, like spinach and lettuce. They are the best kind of light to use as a main light source. High pressure sodium lights, on the other hand, are best used as supplemental lighting. They emit light from the red end of the spectrum and are appropriate for plants that produce flowers or fruit, like roses and tomatoes.

If you aren't certain which lights best fit your needs, the staff at Garden Connections is here to help!