Takeaway: Novice cannabis growers may think that a grow light is a grow light is a grow light. But there are many different types of grow lights out there.
Each type of popular grow light has various attributes that makes it more or less suitable for each particular growing space. Knowing which grow light will work best in your own space, with your goals and budget in mind, will help you decide what will work best over time. Let’s take a look at the more common types of lights people use to grow marijuana.
T5s
T5 grow lights are a type of fluorescent tube. These are a good introductory light to start with as they are relatively inexpensive and do not require large amounts of electricity to run. They do require a ballast, though many starter kits provide the ballast and some even provide a mount so that the light can be raised or lowered depending on the size and stage of growth.
Besides the lower costs of T5s, there are a few other benefits to consider. They do not give off much heat, which reduces the chance of burning of the cannabis’ foliage. Conversely though, they do not give off a large amount of light either. To make the most of T5s they need to be no more than two feet away from the tops of the plants, but due to their lower temperature, can be as close as one inch.
This type of light is often used by cannabis growers during the vegetative stage of growth, typically by utilizing cool white bulbs. If it is the only light available during the flowering stage, then the type of bulb should be switched to a warm or soft white bulb. Many professional growers do use the T5 for the vegetative phase, but switch to another type of light for the flowering phase.
HID
High intensity discharge (HID) refers to a class of lighting that includes high pressure sodium, metal halide and ceramic metal halides. HIDs are the most efficient type of grow light available.
They are however more complicated and expensive to install. HID lights generate a lot of heat that generally needs to be redirected or cooled or a grow room will overheat. This usually means installing some type of fan or cooler with additional ductwork to carry the heat away.
Growers who swear by these lights would argue that it is worth the extra initial setup time and costs as they do not need to be further adjusted as the plants grow like the T5s do. These are screw-in type bulbs that require a special ballast to operate. They also require more frequent bulb changes than the other types of grow lights.
HPS
High pressure sodium (HPS) bulbs are a type of HID. HPS bulbs are typically used during the flowering stages of growth as their light helps with bud development. HPS bulbs are the most efficient of the HIDs. HPS bulbs have been around as a single-ended screw-in type bulbs for several decades.
A more recent addition to the grow light market is the double-ended HPS. This newer type does require a new ballast and is more expensive than the older types of HPS bulbs. They are, however, much more efficient. They last much longer, burn cooler, and have been shown to increase yields as compared to the single-ended HPS bulbs.
MH
Metal Halide (MH) bulbs are also a type of HID. They are used almost exclusively during the vegetative stage as they produce light from the blue end of the spectrum.
LEDs
Light emitting diodes (LEDs), like all of the other types of grow lights, have their pros and cons. They are generally the easiest of all grow lights to install. They just need to be plugged in and they are ready to go. They do produce more heat than a T5, but far less than HID lights. In general this means that no additional cooling apparatus needs be installed.
In regards to setup, they need to be kept at least 18 inches away from the crop. They also have a higher price point than most other grow lights. This can be offset though by the lower operating costs as compared to the other types of grow lights and the extremely long useful life of LED grow lights; some can last for as long as 10 years.