Hydroponic Lighting

Artificial Light

Usually, natural sunlight is used for this important job. However, during the shorter and darker days of winter, many growers use artificial lights to increase the intensity of light (for photosynthesis) or to expand the daylight length. While the sun radiates the full spectrum (wavelength or color of light) suitable for plant life, different types of artificial lighting are selected for specific plant varieties and optimum plant growth characteristics. Different groups of plants respond in physically different ways to various wavelengths of radiation. Light plays an extremely important role in the production of plant material.

The lack of light is the main inhibiting factor in plant growth. If you reduce the light by 10 percent, you also reduce crop performance by 10 percent.

Light transmission should be your major consideration when purchasing a growing structure for a protected crop. Glass is still the preferred material for covering greenhouses because, unlike plastic films and sheeting, its light transmission ability is indefinitely maintained.

No gardener can achieve good results without adequate light. If you intend to grow indoors, avail yourself of some of the reading material that has been published on this subject. If you are having trouble growing good plants, then light is the first factor to question.

Natural Light

A large part of the success in growing hydroponically is planning where to place the plants. Grow plants that have similar growing requirements in the same system. Placing your system 1-2 feet away from a sunny window will give the best results for most herbs and vegetables. Even your regular house lights help the plants to grow. Make sure that all of the lights are out in your growing area during the night. Plants need to rest a minimum of 4 hours every night. If your plants start to get leggy (too tall and not very full), move the system to a spot that has more sun. Once you find a good growing area, stick to it. Plants get used to their home location. It may take some time to get used to a new place.

Lighting Terms and Definitions

Ballast
The electrical components (usually a transformer and capacitor) that energize a high intensity bulb.

Color Temperature
(also known as Kelvin temperature or correlated color temperature)  A measure of color of light emitted by a bulb in comparison to black.  This is used as a general meaure of a bulb's coolness (whiter light) or warmness (redder light).

Footcandle
A unit of illumination equal to the intensity of one candle at a distance of one foot.  Footcandles are usually used as a measure of light received.

Lumen
A unit of illumination; a measurement of light output.  One lumen is equal to the light emitted by one candle that falls on one square foot of surface located one foot away from the candle.

Photoperiod
The relative hours of light and darkness in a 24-hour period.  Some plants respond to a change in day length (photoperiod) in order to grow or flower.

Photosynthesis
The process by which plants use light energy to collect carbon dioxide from the atmosphere and convert it to chemical (growth) energy in the form of carbohydrates.

Metal Halide (MH) and High Pressure Sodium Lamps (HPS)

Metal Halide lamps and High Pressure Sodium lamps belong to the
H.I.D. (High Intensity Discharge) family of lights.
Metal Halide and High Pressure Sodium lamps are used for garden lighting because of their high light output per watt, and the spectral distribution of their light.

Metal Halide / Daylight / MS Lamps - These lamps emphasize the blue / green spectrum to promote vegetative growth. If you have little or no sunlight available these are the systems to use. MS lamps contain a 30% boost over standard Metal Halide lamps in the red/orange spectrum and more lumens per watt than standard Metal Halide lamps.

High-Pressure Sodium - These lamps are primarily red/yellow in spectrum. These are the best lamps available for use in conjunction with natural sunlight. High-Pressure Sodium lamps promote budding and flowering in plants.

Mogul base bulbs are single-ended screw-in bulbs.

HQI bulbs are double-ended metal halide bulbs.

Conversion Bulbs - There are two types:

1) Sodium bulbs which run on Halide ballasts.

2) Halide bulbs which run on Sodium ballasts.

A conversion bulb lets you tailor the light source to the growth stage of the plant merely by changing lamps.

Flourescent Lamps - These lights are perfect for starts and seedlings. They are generally a poor light source for production growth and flowering because of their low lumen output, although they may be used in some instances for small scale systems with low growing plants, ie: lettuce, basils, etc. Plant growth will not be as rapid as under HID lighting due to lower light levels.

High intensity discharge (H.I.D.) 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!

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

• Significantly increase the health, strength, growth rate & yield of your plants.
• Supplement natural sunlight in your backyard greenhouse virtually eliminates seasonal & geographical restraints. In addition, by extending the ''day length'' with supplemental lighting, you will greatly enhance your growing success.
• Your container plants that you have outdoors on decks & 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 one of our light
fixtures 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 lights avail able, so they produce much more light for the amount of power consumed.

If you choose H.I.D. as your source of lighting, you have another choice…HPS or MH.

METAL HALIDE LAMPS - This type of bulb emits a light spectrum which appears blue-white to the human eye. It is the best type of light to be used as a primary light source (if no or little natural sunlight is available). This color spectrum is more conducive for vegetative growth, or starting seeds & cuttings.

HIGH PRESSURE SODIUM LAMPS - These lamps are red/orange in the spectrum. They are the best lamps available for secondary or supplementary lighting (used in conjunction with natural sunlight). This type of light promotes flowering/budding in plants. It is a good multi-purpose light as well. It is ideal for Greenhouses/Commercial growing applications.

CONVERSION LAMPS - A). Sodium lamps which run on halide ballasts - more common. B). Halide lamps which run on sodium ballasts. This type of lamp allows you to tailor the light source to the growth stage of the plant (halide blue light for growth and sodium red light for fruiting & flowering) by merely changing lamps.

FLUORESCENT

This type of light is perfect for starts and seedlings. The latest T5 HO products are great for full-term plant growth.

All of these lights require a ballast to operate and come in a variety of sizes and wattages.

How Do Fluorescents Fit In?

Traditional T12 & 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 & 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. We offer Eco Plus™ brand 150 & 200 watt mogul base fluorescent lamps. These 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 house hold 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.

Which light is right for you?

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 hrs 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.

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!

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.

On average a light system will increase your electricity cost from $8 to $20 per month—the exact amount depends on the size of the system and the number of hours operated. However, since these grow lights are so energy efficient, you are getting huge amounts of light (and growing power) for your money!

Make sure your grow room’s power circuit can handle the power draw. For safety reasons, do not exceed 75% of the rated ability of the fuse/breaker (for example: use no more than 15 amps on a 20-amp circuit).

To calculate your cost, multiply the bulb wattage X hours of operation and divide by 1000. This figure is the number of kilo watt hours of electricity consumed. (Example: a 400 watt bulb running for 18 hours will use 7.2 kilowatt hours). Check your power bill for the cost of each kilo watt hour. Then multiply the number of kilowatt hours by the cost of a kilowatt hour (K/hr) to arrive at the cost per month to run the light in your area.