“Which grow lights should I use?” is one of the most common questions asked when a new grower is getting setup. The answer (as always) is “it depends.” There are three main lighting technologies and each has Pros and Cons. Which is best for you will depend on your situation, goals, and budget.
HID – High Intensity Diode Lighting
High Intensity Diode lights are the main lights used by growers. This is because they produce the most useable light for plants and therefore produce the highest yield/m3 and fastest growth rates. They have also been around for a long time so growers are comfortable with them.
HID Grow Lights come in two different varieties of bulb: HPS and MH. Most growers who use HID lighting will use HPS and MH bulbs in their grow room and change the type of bulb depending on the stage their plants are at in the growth cycle.
HPS (High Pressure Sodium) bulbs emit a wave length that is best for plants when they are in their flowering cycle. HPS bulbs are generally used when growers are ready for their plants to start flowering as the will create the largest and most dense flowers.
MH (Metal Halide) bulbs emit a wave length best suited to plants in their vegetative cycle when the grower wants the plants focused on growing more leaves, branches, and root systems. MH bulbs will grow the body and foliage of a plant faster than an equivalent HPS bulb. Growers will generally use MH bulbs early in their plants’ growing cycle and then change to a HPS bulb when they tell their plants to begin the flowering process.
While HID lights have a number of benefits, they do have some draw-backs. They are big electricity users and will cost more to run than LED of CFL lights. Also, they create a lot of heat so it is important to have good ventilation and extraction systems in place. HID bulbs also degrade over time and should be replaced every 3-5 grows. Because HID lights are so powerful, a separate lighting ballast is required to power the bulbs.
HID lighting systems are the choice for most professional hydroponic and indoor growers, and a great option for hobby growers as well.
HID Lighting Pros: Highest yield per m3. Cheaper than LED lights.
HID Lighting Cons: Create a lot of heat so require a good extraction system. Use a lot of power so are more expensive to run than CFL or LED. Bulbs need replacing every 3-5 grows (depending on how many hours they run for).
Best grow lights for you if: HID bulbs are probably the best lighting option for you if you are looking to maximise yield in the space you have available.
CFL – Compact Fluorescent Lighting
For indoor and hydroponic gardening, CFL lights are another commonly used lighting technology. CFL bulbs are less powerful than the other lighting technologies available. They also cost less and
produce less heat which makes them a good choice for getting your plants started, sprouting seed, and growing clones. They are also a good choice for growers who have a very small space to grow in or who want to grow a small amount without investing too much in equipment.
CFL bulbs come in a range of types, namely the spiral CFLs (which look like a much larger CFL light for your home), and T5 fluorescent tube lighting, which are long straight tubes.
Being cheaper and putting out very little heat does have its drawbacks. Mature plants will have much slower growth rates under CFLs than the other two lighting technologies. For this reason professional indoor and hydroponic growers will use CFLs only for baby plants and clones. However, for hobby growers looking to grow a modest amount on a small budget, CFL lights may very well be the best choice.
CFL Lighting Pros: Cheapest type of grow lights to purchase. Very low heat output meaning that you can have a simple setup without large extraction fans.
CFL Lighting Cons: CFL lights output less power than the other types of lighting, meaning that growth rates will be slower and yield will be less than either HID or LED.
Best grow lights for you if: CFL bulbs will be your best choice for growing clones, seedlings, and small plants OR if you are a hobby grower looking for a low-cost and easy way to start growing indoors.
LED – Light Emitting Diode Grow Lights
The third option is LED grow lights. These share some of the advantages of both HID lights as well as CFLs, however they have some of their own draw backs as well.
Until recently, LED horticultural lighting technology hadn’t progressed far enough to be a good option. This didn’t stop numerous suppliers for selling “LED Grow Lights” that underperformed and led to disappointing yields for growers. However, LED technology has now progressed to a point where LED lighting is a viable choice for your indoor garden or hydroponic setup.
LED lights are more efficient than HIDs in terms of their ability to turn electricity into usable light for your plants. This means that they produce less heat and use less electricity than comparable HID setups. This is gentler on your power bill and makes temperature control easier. The downside is that LEDs will generally produce less yield per m3 than a comparable HID. They are however much more powerful than CFL lighting setups. Further, high-quality LED grow lights are much more expensive to buy than their comparable HID equivalents. Beware lower-priced LED grow lights as they will provide very poor performance and disappointing yields/results.
LED Lighting Pros: More powerful and effective than CFLs. Much less heat output than HIDs. Lower energy use/running costs.
LED Lighting Cons: Less yield than comparable HIDs (regardless of what anyone says – don’t believe the hype!) Expensive purchase price will scare off some growers.
Best grow lights for you if: LED grow lights are probably the best for you if you are growing in an area that is difficult to keep cool, but you still want a good yield. They also might be a good choice for hobby growers who want to keep running costs low and don’t mind the heavy price tag.
Overall what type of grow lights are best for you will depend on your situation, goals, and budget. HID lighting systems are the gold standard, tried and true, and the choice for the vast majority of growers. CFL systems are great for small spaces, small budgets, or for starting your plants. LED systems give better results than CFL but less results than HID; they produce much less heat, but come at a higher price tag.