Talk about lighting your garden, and immediately an argument erupts; what kind of lighting is the best? Tried and true fluorescent, powerful, but power hungry, HID, or one of the new crop of lighting choices like LED, induction or plasma? Since there is no way any one of these is definitively better than the others for all situations, I thought I’d use this month’s column to navigate you, my cadre of crop-masters, through the different choices and help you with the decision about which is best for you in your specific setup.
We’ll begin with fluorescent lighting – the good ol’ fat tubes, the so-called T12s. They are decent light producers but they don’t provide much intensity. If they are much more than a few inches from the leaves, they aren’t doing your plants much good. However, they do run cool enough to just about touch your plants so you can get them nice and close. Similarly, compact fluorescent, or CFL lighting, is also good for lighting plants and growers report better light penetration with these. They’re quite a bit better in terms of light per watt, too. Skinny tubes (the T5 and T8 types) are nearly as efficient as CFL and provide a lot of light over a good area. Paired with a proper reflector, they can provide excellent vegetative light and even adequate flowering light if you train your plants to be short and squat. Limitations include low intensity and a light spectrum that isn’t ideal.
Moving way up the intensity scale, the brightest and currently most powerful lighting type is High Intensity Discharge (HID). These are the bulbs in streetlights and football stadiums, and man, do they make some light! The orange ones are High Pressure Sodium, or HPS, and the bluish ones are Metal Halide, or MH, owing to the different mixes of metals in the bulb. While there remains some debate, it’s generally accepted that MH is better for veg, and HPS is the standard for blooming. These bulbs are power hungry, and they’re HOT - a 1000-watt bulb with its ballast is using about the same power as a hair dryer and is producing nearly the same amount of heat! If you use these, and millions do, be sure to address your ventilation and cooling needs, otherwise you will find yourself building a sauna instead of a growroom. In addition, the spectra that these bulbs put out is not ideal for growing plants - but these are the brute force lights of the industry; you pour on the lumens, and good things are bound to happen.
Moving up the tech ladder, we come to the newest darling of the gardening industry, LED, for Light Emitting Diode. These lights last and last, and the light they produce is VERY focused; first, they aim the light at a relatively narrow angle, 120 degrees as opposed to 360 degrees. Second, they run cool enough to touch, even the higher wattage systems aren’t hot. Third, they are tuned to emit light in extremely specific wavelengths, only those that have been shown to provide the most response by plants. So why doesn’t everyone have them? Simple…up front costs are still steep. Also, the narrow wavelengths are so specific that it’s taking some time to develop LED lights with spectral mixes that will effectively flower plants. That said, these problems are being overcome and just like LED televisions, the prices are dropping every month.
Next up we have Induction lighting. This is a new tech based on a very old principle, and shows great promise for several reasons. They last a very long time, and run cool and very efficiently like LED, but unlike LED, they emit a broad spectrum of light. However, they do not provide the intensity of light like HID does, and since they’re fairly new and have yet to gain widespread acceptance, they are also very expensive.
This brings us to the newest kid on the block - plasma lighting. This is where things take a turn for the Star Trek; our physics geek friends will tell us that there are four types of matter; solids, liquids, gases, and…plasma. Plasma is what makes the sun shine so brightly. So far, it looks like plasma lighting is very good at providing a broad spectrum of PAR, or Plant Active Radiation, light, and promises to be both longer lasting and much more efficient than HID varieties. However, the jury is still out because of their small size and respective lack of intensity. And of course, since it’s new, it’s expensive compared to the more widely used options.
There is much more detail about each of these choices and I encourage you to do your homework on the different types.
As a starting point, here are the standards: For the vegetative phase, cooler, bluer light is recommended. For tender shoots and cuttings, you can’t go wrong with trusty fluorescents - they’re cool, and the softer light is good for encouraging the little ones to put down roots and get going. For fast vegetative growth, T5 lights, CFLs and even carefully placed MH HID bulbs (not too close!) will definitely fill the bill. LED is catching on fast here as well. When moving to flower, while you can use CFL and LED in smaller setups, for bigger areas (6 sq. ft and up), you will want to seriously consider HPS lighting as it provides the light intensity plants crave to set fruit and flower properly.
There is much more detail about each of these choices and I encourage you to do your homework on the different types. Also, based on the size of your room, your personal limitations on cost, power bills, heat buildup and cooling needs, you will need to carefully weigh each option to be sure it will suit your needs.