Why use supplemental lighting for indoor or greenhouse gardening?

High intensity discharge lighting has traditionally been used only by commercial growers in large scale greenhouses. These business savvy professionals have long understood the exceptional benefits of supplemental, artificial lighting for plant growth. From stronger, healthier seed starts, into faster maturing, vigorous plants that offer much higher yields and more spectacular flowering than can be achieved without supplemental lighting. H.I.D. lighting not only supplements sunlight, but can actually replace it during long winters where sunlight is in short supply. It is very energy efficient and the cost of operating one of our light systems is comparable to using one of your kitchen appliances.

Plants need light for proper growth. The light spectrum range produced by artificial light (particularly H.I.D. light) enhances the natural light derived from the sun by many times over. The result, when combined with proper nutrients, is nothing short of amazing. And the best news is, this technology once available only to the commercial market is now available to you.

All this being said, what can supplemental lighting do for a home, hobby grower?

Significantly increase the health, strength, growth rate and yield of your plants
Supplement natural sunlight in your backyard greenhouse virtually eliminates seasonal and geographical restraints. In additions, by extending the "day length" with supplemental lighting, you will greatly enhance your growing success.
Your container plants that you have outdoors on decks and patios during the summer can be moved indoors during the winter under H.I.D. or high output fluorescent light allowing them to thrive year round.
Indoor gardening - Why settle for gardening just a few months of the year? By using a light fixture as a primary light source indoors, you can enjoy the hobby of gardening all year long!

High Intensity Discharge lighting systems have revolutionized indoor gardening in the last two decades. They are the most energy efficient grow light available, so they produce much more light for the amount of power consumed.

Traditional T12 and T8 fluorescent fixtures are simply not powerful enough to light an area more than 8" - 10" below the bulb. With the recent introduction of T5 technology, T5 linear fluorescent's can now put out a respectable 92.6 lumens per watt. T12 lamps typically put out about 30 lumens per watt. T5 fixtures are excellent for starting seeds and cuttings but are also able to produce enough light for full term growth. Because of their minimal heat output, they can be placed very close to the plant canopy to maximize the light output.

High wattage self ballasted grow lamps have become quite popular in the recent past. The EcoPlus brand 150 and 200 watt mogul base fluorescent lamps put out about 70 lumens per watt. They are an excellent choice to start seeds or to use over a small garden area.

Incandescent lamps - these standard household bulbs do not emit enough light, or the proper spectrum, to be used by serious gardening enthusiasts. They are not very efficient, using a considerable amount of power for the light they emit. They are typically only about 15 lumens per watt.

Most gardeners use at least 25 watts per square foot of garden space. You may need less if your light is used to supplement natural sunlight, or if you are growing a plant that does not require as much light (ie, lettuce). However, many gardeners prefer to double or even triple the recommended wattage to achieve faster growth rates. There is really no such thing as too much light, but using a big light in a small space will sometimes result in high temperatures that are difficult to control. Keep in mind that plants need periods of darkness too. Most indoor gardeners use lighting from 10 - 16 hours per day.

Hanging Height - Keep an HID bulb about 30" - 36" above the top of your plants. This is an average distance... lower wattage bulbs may be placed closer, while higher wattage bulbs may need to be placed further away. Higher wattage bulbs provide more intense light for large growing areas. Lower wattage systems are used for smaller garden areas. Note: The height of the reflector/fixture above the plants will also affect coverage area.

Average coverage area by wattage:

150/175 watts: 2' x 2'

250 watts: 3' x 3'

400 watts" 4' x 4'

600 watts: 6.5' x 6.5'

1000 watts: 8' x 8'

A fluorescent fixture can be placed much closer to plants than a H.I.D. fixture because it produces very little heat. You should place your fluorescent lights 12" - 24" above your plants depending on the number of lamps in your fixture and the desired light level. Keep in mind that the light levels are reduced significantly as you raise the light source above your plants.

High Pressure Sodium (HPS) or Metal Halide (MH): If you choose H.I.D. as your source of lighting you have another choice, MH or HPS. Metal Halide bulbs emit a light spectrum which appears blue-white to the human eye. This color spectrum is more conducive for vegetative growth, or starting seeds and cuttings. High Pressure Sodium (HPS) bulbs emit a spectrum which is more concentrated in red/orange light. This color is ideal for the fruiting and flowering stage of a plant's development. It is a good multi-purpose light as well.

Only part of solar radiation is used by plants for photosynthesis. This active radiation (PAR) contains the wavelengths between 400 and 700 nanometers and falls just within the so called visible spectrum (380-770 nm). The total visible spectrum is perceived by us humans as white light, but with the aid of a prism, we see that the "white" light is actually separated into a spectrum of colors from violet to blue, to green, yellow, orange and red. Plants use the blue to red light as their energy source for photosynthesis.

Your style of gardening will determine the best type of light for you. But, whichever model you choose, you can be assured that your investment into the lighting technology used by the professionals will be rewarded by increased, nutrition packed yields, lovelier flowers, healthier plants.

Graph showing percent of photosynthetic activity