The best hydroponic grow light for you will depend on a number of factors. These include the cost of the light, the energy cost of running the light x number of hours a day. The environment that the plant is in and what stage of growth you are trying to facilitate.
Florescent and Incandescent grow lights
While they are cheap to buy they are rather inefficient as hydroponic grow lights. Incandescent and Florescent grow lights are fine for low-light plants where limited results are expected. However the light is of a low intensity and they produce a low level of lumens per watt and are therefore less efficient than High Intensity Discharge Lights (HID) or Light Emitting Diode Grow Lights (LED grow lights). Incandescent lights have a much shorter usable bulb life than high-pressure sodium lights and LED grow lights. They also have approximately six times lower light output per watt of energy consumed than a High Pressure Sodium Light.1
High Intensity Discharge Lighting (HID)
High Intensity Discharge lighting consists of a lamp, reflector and power supply. They are designed to produce a high output of photosynthetically active radiation (PAR) for the amount of power consumed. It is not just the quality of the light but the quantity that is also important and High intensity discharge lights can produce both.
Commercial growers and some of the world’s premier growers use High Intensity Discharge lights and produce impressive results that would be impossible with conventional florescent and incandescent lamps.
Until recently High Intensity Discharge lighting for horticulture has not been cost effective. As a result of new lighting products by manufacturers like Hydrofarm and Sunlight Supply, lighting costs have been significantly reduced making the use of such lights profitable.
High Intensity Discharge lights are designed to cover the PAR spectrum (Photosynthetically Active Radiation). The wavelengths of light most important for photosynthesis to occur are the red and blue light spectrum, red being 600 – 680 nm and blue being 380-380 nm. These wavelengths are considered the most important for photosynthesis and HID lights cover these spectrums well.
There are two types of HID lamps which emit different colour spectrums:
Metal Halide Grow Lamps
Metal halide lamps emit light at the white/blue spectrum. Metal Halide lamps are best used as a primary light source if there are no other light sources and little or no natural sunlight is available. They consume large amounts of energy but produce significant quantities of light.
Advantages of Metal Halide Lamps (MH)
- Best when there are no other light sources
- Promotes compact vegetative growth
- Best for vegetative growth
- Emit high levels of blue light promoting growth of leafy plants
High Pressure Sodium Grow Lamps (HPS)
High-pressure sodium grow lights have a long usable bulb life and are a much more efficient means of producing light than standard incandescent grow lights. They emit a yellow/orange spectrum of light and have a yellowish glow. They are good when used in combination with other light sources such as weak sunlight during the winter months.
Advantages of High Pressure Sodium Lamps (HPS):
- Work well with other light sources (natural sunlight etc)
- Best for flowering/budding stages of growth
- Ideal for greenhouses and commercial growing applications
- Emit high levels of red light good for flowering and fruiting plants
The Son Agro and Hortilux HPS lamps add an additional 30% blue factor to their spectrum making them more efficient than other HPS lamps for solo use.
You can also buy High Pressure Sodium to Metal Halide conversion bulbs. These can switch from emitting Metal Halide light during vegetative growth then let you switch back to High Pressure Sodium for the flowering/budding stage of growth.
LED Grow Lights
LED grow lights are the most efficient means of producing light for plant growth as the light produced is specifically designed to target narrow wavelengths required for photosynthesis also most of the energy is not lost in the form of heat like other grow lights. LED grow lights have the highest PAR value (photosynthetically active radiation) of all grow lights. The downside of LED grow lights is that they are expensive to buy and while being the most efficient, the cheaper models don’t produce enough lumens to be effective for growing a decent size crop.
Advantages of LED Grow Lights:
- Produce less heat than other light sources which can damage plant and dry up hydroponic solution.
- Much longer bulb life than other lamps. Typical lifetimes quoted are 25,000 to 100,000 hours.2
- Lower energy costs due to higher efficiency
- No costly cooling system required unlike Halide Lights which get hot
- LED grow lights do not contain the harmful mercury-filled bulbs that exist in some other grow lights.
- Powerful LED grow lights have been shown to produce higher yields and vegetative growth
- Grow Light, Wikipedia [↩]
- Light emitting Diode, Wikipedia [↩]
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