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Plugged in for Bigger Yields

One size rarely fits all. That’s true with pants as well as plants. Choosing the right lighting system for your indoor garden is critical, and your decision on setup will have a big influence on your harvest.

Ready to begin? Let’s first answer a few questions, to make sure you’re heading in the right direction.



What Are My Yield Expectations?

This is the first question, and it’s a biggie. Keep in mind the amount of space you are able to devote to your growing. For big commercial-sized harvests, you will need plenty of space and thousands of watts of electricity for HID (high intensity discharge) lighting systems such as HPS (high pressure sodium) and MH (metal halide). If space is limited and you still demand big yields, look to vertical gardening methods, which use less floor space and take advantage of the vertical height of an area, which can increase the crop volume.

If you are just looking to supply yourself, your family, and perhaps a few select friends with supplementary greens, you may not need the power and intensity of HID lighting, which requires lots of electricity and generates heat. It also needs to be vented using high-powered fans, which can be noisy and obtrusive. Instead, consider T-5 fluorescent lighting or, if your budget allows, high-tech LED lighting. These can offer some respectable lighting yields while avoiding all the heat and noise problems associated with HID setups.

Do I Have Space Limitations?

If you are forced to cramp your garden into tighter spaces, it’s probably best to avoid HID lighting. HID lamps such as MH and HPS produce lots of heat; it’s like running a heater of the same wattage in a confined area. Furthermore, you need to keep some distance between the tops of the plants and the lights: typically 12 to 30 inches depending on the wattage used. Add to this the fact that you need to keep a safe distance between the ceiling and the lamp reflector; you can run out of vertical height for plant growth and development very quickly.

If the space has ample height but is tighter in linear dimensions, you may still be able to use high-yielding HID lamps with the assistance of air-cooled lamp reflectors. These reflectors seal off the heat generated from the lamps with a protective glass lens and use fans and ducting to extract the heat away from the lamps and send it outside, before it has a chance to warm up the growing area. Water-cooled lamp reflectors are widely available and work very efficiently at capturing heat from HID lighting. Each method has its advantages. Gardeners cohabitating with their indoor garden may appreciate the fact that water-cooled lighting can operate much more quietly than fan cooling with air-cooled lamp reflectors.

If you have vertical limitations, investing in a high-quality LED lighting system can give you respectable results while eliminating heat issues. It also allows the LED fixture to come much closer to the tops of the plants and the fixture closer to ceilings, giving more room for plant production. T-5 flourescent lamps also work very well in tighter spaces. They will still generate some heat that needs to be vented away, however, but not nearly as much as the heat intensity created by HID lighting.


- HIDs

The Upside
superhot high intensity discharge (HID)
lamps can deliver incredible light
intensities indoors.

The downside
HIDs produce a lot of heat. If you cannot effectively manage this considerable amount of heat, use a cooler source of light for your garden.

If you’re in the process of selecting an HID system, you can buy a complete kit or cobble together the components individually. A complete system consists of ballast and enclosure, power cord, lamp cord, reflector and socket or lamp holder and socket, and the correct wattage and specification of lamp (light bulb) for the ballast.

There are two basic types of HID ballasts presently available to indoor gardeners: digital/electronic, and magnetic/core and coil. The digital/electronic units are a relatively newer technology; although a little more expensive, they prove to be superior to the older style magnetic/core and coil ballasts in many respects. First, digital/electronic units can run either MH or HPS lamps from the same unit, making them more flexible. Some units even have dimmer or wattage output capabilities, allowing the grower to increase or decrease light levels, electrical consumption, and heat output. Furthermore, they produce a higher quality of light for plants using the same HID lamp as with magnetic/core and coil ballasts. While improving the light quality delivered, digital units can make lamps burn brighter, creating more available light for growth. They also help to reduce power utility bills versus magnetic/core and coil units. It’s worth the time to take a look at different ballasts from different manufacturers and see what people who have bought them are saying.


A. Duct flanges allow for hotter air to be exhausted away from the growing area, as fresh cooler air is drawn through over the lamp. Provided there are enough CFM (cubic feet per minute)of air moving through the fixture, this helps to reduce heat build-up in the growing environment.

B. This air-cooled model uses a glass tube rather than a lens to help vent heat out of the growing area before it ever has the chance to enter. This provides effective cooling, and helps maintain a higher rate of airflow as there is less friction loss of air movement with a straight tube rather than with conventional air-cooled reflectors. This innovative design still provides optimum light coverage because it uses a four-sided reflector design.

C. Lamps run significantly cooler, preventing overheating of the growing environment, which can damage plants. The life of the bulb may also be improved due to a reduction of heat build-up around the lamp in the enclosure. Make sure to use the correct wattage lamp for the correct size of reflector.  Mogul socket extensions are available to improve the placement of lower wattage lamps in larger fixtures.

LED Lighting

- LEDs

The upside

Light emitting diodes (LEDs) are not a new technology, but their development to higher wattages and suitability for growing plants is. LEDs have the potential to be ultraefficient in producing optimal spectrums for plant growth while adding little, if any, additional heat to the growing environment. Because they run so cool, it’s easy to elevate CO2 levels in the garden, which further increases yields and growth rates.

The downside

As LEDs for crop lighting are a newer technology, consumers need to be aware that the effectiveness of the technology will only be as good as the manufacturer that is supplying the unit. Over time, LEDs may become standardized, similar to HPS and MH lighting systems. However, at present it pays for consumers to take their time and do their research when selecting a particular LED lighting product. Hint: Look for quad-band technologies.

LED (light emitting diode) lamps are real workhorses. They can operate for up to 50,000 hours without needing replacement. Compartively, HID and T-5 fluorescent bulbs lose their intensity relatively quickly and need to be replaced every six to 12 months.

The result is that indoor growers have learned to love LED. Buyers need to be aware, however, that the quality and performance of LED lighting systems promoted for plant growth varies greatly, while HID lighting systems have become relatively standardized.

Expect to pay a pretty penny for units that work well and will give you heavier yields of high-quality crops. If you are at all serious about your crop, do not use LED systems in which the individual diodes are less than 1 watt each. Also, the older style blue and red-only diode arrangements will not perform nearly as well as units that incorporate orange and UV diodes into the arrangement.

You really do get what you pay for when it comes to LEDs, don’t waste time with low output models if you want to have harvests that compare to HID-lit gardens. The technology is expanding at a fast rate, so improvements are constantly being made.

LED lighting can give spectacular results and avoid many of the common problems associated with HID gardens: excessive heat, high electrical consumption, and the noise that’s associated with moving large volumes of air through ducting with high-powered fans. You should most definitely consider LED.

Stealth Grow LEDStealth Grow LED

Stealth LED*Stealth LED*A. The individual diodes or LED chips are arranged onto the LED lighting board.  By blending different diodes and chips with different lighting spectrums, manufacturers are able to create precise wavelengths of light for plant growth, helping to make LEDs very efficient and cool running.

B. A series of small powered fans help keep the circuitry that drives the LEDs from overheating, improving light output. LEDs and their fixtures generate negligible amounts of heat, so little additional ventilation is required in most situations.

C. A thin sheet of glass helps to protect the diodes/chips from damage or dirt and dust from collecting and blocking light output. The loss of light is extremely low, perhaps less than a percentage point.

Stealth LED* The intensity and area covered by next-generation high-output, quad-band LEDs is far superior to early generation, dual-band LED crop lighting systems. The diodes/chips are greater in number and spectral diversity and are of much higher wattages.

T-5 Fluorescent Lighting

- T-5s and CFLs

The upside

Tech improvements allow growers to cultivate even the most light-loving varieties.T5 high output fluorescents (CFLs) tend to run cooler than HIDs, and intensity is not as strong. Fluorescent lighting often offers a superior spectrum over the majority of HID lamps.

The downside

While fluorescent lighting can produce a very high quality of light for plant growth, it lacks the intensity required for larger plants at greater distances from the lamp fixture versus HID and high-output LED crop lighting. Also, while cooler running than some light sources, T-5 and CFL lighting will generate significant levels of heat that in many instances will require ventilation to keep garden temperatures optimal.

People have been growing houseplants under fluorescent bulbs for decades. Traditionally, these lights have not been very well suited to producing good yield levels in high-light loving plant varieties such as tomatoes. The new digital T-5 fluorescent lamps and fixtures, however, are far superior to their conventional predecessors for plant production.

The average fixture used for plant growth measures 2 x 4 feet and typically uses 6- to 8-foot high output (HO) T-5 fluorescent lights. While not as intense as HIDs, the light spectrum is better for plant growth versus HPS and MH lamps. Growers can also create custom lighting spectrums by creating different arrangements and ratios of T-5 lamp colorations; when the light reaches the plants, the spectrums have blended together.

Don’t expect to yield as much as with HID lighting, although if you keep your plants less than 12 to 18 inches tall by harvest, yields can be of respectable weight per square foot and are usually of very high quality, although perhaps not as dense or thick as with HIDs or high output LEDs. Plants should be kept shorter or have the bottom growth pruned off using fluorescent lighting, because the intensity of fluorescent lighting drops very quickly with distance travelled, making shorter plants more productive with this type of lighting.

Note that a combination of LEDs and T-5s can produce good harvests per square foot of lit growing area very efficiently for the hobbyist looking to grow smaller quantities of very high quality crops.

CMYK Plugged In SpreadCMYK Plugged In Spread

A. High output T-5 lights can be very bright! When multiple lamps are housed in a highly reflective and well-designed enclosure, the result is a consumer-friendly plug-and-play technology that can provide very high light levels to an area similar in size to that of the reflector; for example, 2 x 4 feet.

B. The fixtures house both the lamps and the ballasts, so adequate support is needed. With any crop lighting fixture, anchor hooks, chains, etc. into studs rather than dry wall to support the weight.

C. This specialized T-5 fixture is designed to maximize lighting levels reaching the tops of the plants. Each T-5 fluorescent light tube has it’s own reflector built into the fixture to help accomplish this.

D. For times when lower lighting levels are required or when temperatures may need to be reduced, this switch allows growers to shut-off a portion of the lights, while other lights within the same fixture remain running. This is very handy for propagation purposes where initial light intensity requirements are relatively lower.


1. Get a good light meter.

Choosing a light meter is like choosing a GPS device: If it fails or gives false readouts, you will be lost. So get a decent one. Most entry-level light meters cost around $100. The best give readouts in photon flux density or microeinsteins.

2. Measure correctly.

It makes no sense to capture light-level readings directly under the lamp; naturally, that’s where they will be highest. Take readings from various points in the plant canopy to determine the average level of light reaching all parts of the plant canopy.

3. Use the right light at the right time.

Plants that receive the right amount of light energy during the right phase of growth will produce bigger yields and higher crop quality. Plants that are stressed due to poor light levels are prone to insects and diseases, which further reduce yield potential, and harvest quality often suffers as a result.


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Erik shows his growth chamber, lit by two LED lights, supplemented by fluorescent lighting
Last modified on Tuesday, 16 October 2012 14:01

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