New Horticulture Grow Lights: CFL and LED Systems
Many orchid growers use fluorescent lights (FL) or high intensity discharge (HID) lights to provide exclusive or
supplemental lighting for their plants. A variety of FL bulbs are available, from inexpensive "shop lights" to the well
known Grow-Lux or long lasting Verilux full spectrum bulbs to the new high output HOF systems which provide
approximately three times the amount of light as standard FL bulbs. The HID systems are popular in commercial and
hobby horticultural lighting owing to their ability to produce more light than FL setups. They provide more lumens (light
power) per watt of electricity and use 250 to 1000 watt metal halide (MH) or high-pressure sodium (HPS) bulbs in
reflector fixtures. MH systems are recommended for plant growth applications where there is little or no natural light
available. HPS systems promote flowering and typically are used where some additional natural light is available (e.g.
in a greenhouse). Some HID light systems have both MH and HPS bulbs in the same reflector fixture.
[Note: Street, warehouse and security lighting systems that emit a yellow glow are from low pressure (LP) sodium
lamps. These LP sodium lamps produce light only in one very narrow portion of the light spectrum at 589 nm. If used
for growing plants, these lamps must be used with a metal halide lamp to stimulate photosynthesis and chlorophyll
synthesis.]
There are two other relatively new lighting systems now available that are worth investigating. These are energy
efficient compact fluorescent lamps (CFL) and light emitting diode (LED ) grow lights.
Compact Fluorescent Lamps (CFL)
The CFL system is a variant of the normal tube FL setups. The bulb, pictured below, is about 14 inches long and fits
into a reflector fixture that is essentially the same as an HID fixture. The ballast is built into the base of the bulb.
The CFL setup is available in several configurations, For example, FarmTek offers a high output (HO) CFL fixture
with a "wide spectrum" 125W or 200W bulb ($89.95 and $159.95, respectively).
[www.farmtek.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10052&storeId=10001&langId=-
1&division=FarmTek&productId=65561].
I purchased the 125W system for under $100 with shipping. Charleys Greenhouse offers 125W CFL systems for
$139 with either "daylight" full-spectrum HO compact bulb (K6400 for growth) or a "warm" (K2700 for flowering) HO
compact bulb. [www.charleysgreenhouse.com] The 125W CF lights cover a growing area of about 4 sq. ft. with
additional coverage for low light plants. The long lasting bulbs run cool and can be placed close to the plants to
increase light intensity if needed. The amount of electricity used is about the same as for a standard incandescent
reading lamp. (It is estimated that they cost about a dime a day to operate.) Hydrofarm [www.hydrofarm.com] also
offers CFLs in two distinct spectrum ranges in 125W and 200W versions.
Interestingly, if has been reported that when used in-conjunction with traditional HPS bulbs, CFLs produce one of the
best light environments there is for growing plants. The combination has the capability to dramatically boost
photosynthesis, improve plant health, enhance fruit quality and size and increase overall yields. [www.simplyhydro.
com/article_6-6.htm]
LED Grow Lamps
While LED grow lights have been used in horticulture applications for several years, a US patent was granted in July
2005 to SolarOasis for the first commercial LED Ruby Gro-Bar grow lighting device.
[See www.freepatentsonline.com/6921182.html}
Patent Abstract
"A first set of orange LEDs with a peak wavelength emission of about 612 nanometers, a second set of red light
emitting LEDs with a peak wavelength of about 660 nanometers, and blue light LEDs. Two beam spreads, 15° and
30°, were provided for both the 660 nm LEDs and 612 nm LEDs. When directed perpendicularly upon tops of the plant
leaves, 10% light transmission occurred through the leaves for the 30° LEDs, and 80% light transmission for the 15°
LEDs. Thus, fully 50% of the orange/red spectrum primarily used for photosynthesis was transmitted through the
upper leaf canopy, making it available to support photosynthesis in leaves below. LED lamps are positioned at varying
distances from the growing plants for controlling plant growth rates that vary with these distances, thereby to control
plant inventory, because growth of plants can be greatly slowed to preserve them during periods of slow sales."
SolarOasis pioneered the development of new LED grow light technology that drastically reduces the cost of growing
plants under artificial light. Some clips from the company website [www.solaroasis.com/index.html]
and other sources include the following.
• "The SolarOasis Ruby Grow Bar gives home and commercial plant growers an energy efficient, low heat alternative
to conventional plant grow lighting. Its lightweight, compact design delivers years of use."
• "The SolarOasis Ruby Gro-Bar provides the ideal way to grow plants indoors. It's sleek, high tech designer look
compliments any decor. Featuring three SolarOasis Ruby Grow Lights, the Ruby Gro-Bar mounts easily with two
screws to most surfaces, making a great under-cabinet plant light for the kitchen."
• "The Gro-Bar may be mounted directly above your plants, much like conventional plant growing lights, but unlike
other grow lights they can also be mounted vertically on a wall to virtually surround your plants with light."
• "Conventional grow lights consume between 100 watts and 1,000 watts of power to operate. Each SolarOasis Ruby
Grow Light uses less-than 2 watts of power. This energy savings becomes more and more important as energy costs
continue to rise. On average, SolarOasis grow lights use 33-times less energy than comparable metallic vapor lights
(based on 3 Ruby Gro-Bars per 400 watt MH light). Three LED Gro-Bars containing three LED lights, used 16-hours
per day, at $0.10 per KilowattHour, will cost about $21 per year to operate."
• "Based on data published by the manufacturers of components used in the LED grow light, the expected SolarOasis
bulb life is 20,000 – 100,000 hours. This is ten to fifty times longer than typical glass grow light bulb life expectations."
The SolarOasis Ruby Gro-Bar (GB 16-1) is available online for $159.95 from SolarOasis [www.solaroasis.
com/grow_shop.htm. It can also be obtained from www.cleanairgardening.com/growlight.html.
Individual Pro-Grow LEDs customized for growth or blooming are also available from SolarOasis.
Happy Growing!
Chuck VanDyke (cvandyke@andrew.cmu.edu)