Choosing what kind of hydroponic grow lights you will use for your grow system is one of the most important decisions you will make as a hydroponic grower. Photosynthesis, the process by which your plants will process nutrients and grow, relies entirely upon the availability of quality light. Choose the right light, and you will enjoy a faster harvest and a bigger yield time after time. Choose poorly, and you will most likely see your plants struggling.
Here are the four most common hydroponic grow lights used in modern gardens, and the benefits of each.
- Fluorescent Grow Lights
Fluorescent lights are typically used in smaller or amateur gardens, and are extremely limited in their usefulness. Since they only produce white light and are low intensity, they can't deliver the range of light needed for most plants to grow to their potential. They are therefore only really useful on seedlings and clones. Since they do not give off much heat, they can be placed as close to the plant as you'd like, but most hydroponic professionals recommend a distance of between four to six inches. Fluorescent grow lights are typically very inexpensive, but their bulbs must be replaced frequently, which can add up to much more cost over time.
- High Intensity Discharge Grow Lights
Because they offer a broader range of colors on the light spectrum, and thus more closely imitate natural sunlight, High Intensity Discharge (HID) lights are much more appropriate for general hydroponic growing. They do, however, produce a great deal of heat, which may require purchasing cooling fans to keep your plants safe.
There are two kinds of high intensity discharge lights: metal halide grow lights and high-pressure sodium grow lights. Metal halide lights can emit light on the blue end of the spectrum, and are more ideal for the vegetative stage of plant growth, while high-pressure sodium lights emit light on the red end of the spectrum and are more commonly used for the flowering stage. High-pressure sodium grow lights are also ideal for use on fruit bearing plants and vegetables.
- LED Grow Lights
A LED (Light Emitting Diode) light emits illumination through processing a current in one terminal and out another, forming a simple semiconductor.
LED lights have a number of practical advantages over more common grow lights. Because they produce such little heat, they have little risk of burning your plants; they do not require you to additionally purchase cooling fans. LED grow lights require a larger up front investment, but since they can last between seven to ten years before you need to replace them and use a fraction of the energy of other kinds of lights, they can actually save you money in the long run. Some studies even show that LED lights are even more effective for hydroponic gardens.
LED lights are typically offered in a variety of colors to use at appropriate stages of vegetative growth. There is also available a green LED light, which is "invisible" to plants, and would therefore allow you to observe and maintain your hydroponic garden without interrupting your plants' photoperiod.