Selecting the Right Grow Light

In hydroponics, natural sunlight is replaced by specialized "grow lights" which are designed to emit the spectrum that the plant needs most. The type of grow light you need, obviously depends on many factors, such as the kind of plant and the plant behavior that you are trying to encourage.

To grasp the concept of grow lights, it helps to know a little bit about color temperature and how it affects plants. In the field of plant lighting, "temperature" means color, and not heat. Just as in other applications of heat and cold, the color spectrum is measured in degrees Kelvin - but the distinction is, higher temperatures are considered "cooler," and lower ones, "warmer." The temperatures that largely resemble that of natural sunlight are those ranging over 5000K, and is seen as blue on the color spectrum. Fascinatingly, the reds, oranges and yellows are lower temperature, within the range 2700K and below. Note that leafy vegetation does better in the 6000K range (in essence, full sunlight) while flowering and fruit-bearing plants need the temperature to be around 4800K - those considered in the cooler blue zone. Furthermore, when plants are flowering and reproducing, they are drawing more from the orange-red color temperatures, about 2700K. With this, it's clear that the right grow light is very important to a plant's well-being.

The 3 most common classifications of grow light used in hydroponic gardens are designed toward the color temperatures most needed by plant life. The Metal Halide bulb is one of the most popular. If you like a grow light that resembles true sunlight the closest, then you must go for High-Intensity Discharge (HID) bulb, Metal Halide bulbs. As mentioned earlier, this type of grow light is very good for leafy plants. The High Pressure Sodium bulb (also another HID bulb) is your second alternative. Emitting the orange-red part of the spectrum (about 2200K), these bulbs are most appropriate for flowering plants but do not encourage full foliage. Usually, these bulbs are used in combination of other bulbs or natural light - and are not used as a standalone. The 3rd most popular bulb is the fluorescent either high-output or low-output. Not as "powerful" as the HID bulbs, they can still cover the spectrum well, with the added advantage that they can be placed close to the plants since they emit so little heat.

Today, LED bulbs have been designed, some of which claim to take care of the full range of color temperature for plant life with almost no heat. The only major fallback is, they are usually very costly - and many less costly bulbs are available that can do the job just as perfectly.

To conclude, most hydroponic gardens today use a combination of different bulbs for the various phases of plant growth. Refer to your retailer for the best grow light combination that can address your needs.