Cannabis Grow Lights Explained

Grow lights have taken cannabis cultivation to a whole new level since they became widely available in the 80s, up until that point most cannabis was grown outdoors. Naturally occurring marijuana plants flower annually with the seasons and when grown indoors the plants require specific light types and cycles that mimic natural light conditions. Indoor growing gear such as lights and fans require space, safety measures and obviously a power supply.

Most lighting systems require a ballast box to regulate the power being given to the bulbs. Generally, a ballast box will contain a capacitor, transformer and a connection wire. Most lighting systems come with the ballast box attached to the light fixture or connected via a connection port. Ballasts must be treated with care; they produce a lot of heat and can easily burn through carpets and curtains.

When growing cannabis indoors most people are dealing with space restrictions such as a cupboard or grow tent. To illuminate theses areas growers will usually setup one of the following lighting systems.


Fluorescent Lights

Fluorescent Lights and CFL (Compact Fluorescent Lights) are often used in clone production. Cloning marijuana 'mother' plants is a common practice and fluorescent lights are perfect for nurturing these clones as they give off less heat than the more common HID lighting systems.


High Intensity Discharge or HID

High Intensity Discharge lighting systems are by far the most popular source of artificial light on the market. The reason HID lighting systems are so widespread is that they are extremely powerful, producing enough light to penetrate the higher canopy and provide light to the lower branches of the cannabis plants. These lighting systems work great for both the vegetation and flowering stages of the plant's life cycle and are known to

produce big yields. Generally HID lighting systems require reflectors to evenly spread the light throughout the growing area. Within the category of HID lights there are two subsets to consider:

Metal Halide or MH

Metal Halide bulbs are perfect for inducing growth during the vegetative stage of the plant's life cycle. They emit a great deal of blue light which helps the plant to grow short and stout. There are many MH bulbs available and many are tailored specifically to the vegetative growth stage of the cannabia plant.

High Pressure Sodium

High Pressure Sodium bulbs are used throughout the flowering stage of the marijuana plant as well as other plants that flower or produce fruit. Generally speaking, HPS bulbs are preferred above MH for both the vegetative and flowering stage because they are much more powerful and produce huge yields. This is due to the fact that HPS bulbs produce more output (lumens/light) per watt than MH bulbs.


Light Emitting Diodes or LEDs

LEDs are fast becoming the go to grow light for the modern marijuana grower. These lighting systems utilise solid state lighting technology to produce light as opposed to using filaments like Halogen bulbs or gases like the HID bulbs. LED’s use less electricity than both fluorescents and HID lighting systems, which makes them perfect home cannabis cultivation projects. As well as producing cheaper electricity bills LEDs also produce less heat than other lighting systems and can, therefore, be used within smaller growing areas and be situated closer to the plants. Some LED lighting systems even have features that allow for customisable spectral output, making LEDs suitable for both the vegetative and the flowering cycles. The only real drawback to using LED lighting systems is the price tag; lights of this kind should be looked at as a long term investment. LED bulbs can last up to 15 years (which justifies the price) and this reliability is causing LED lighting systems to gain a lot of attention from indoor growers.


Wattage isn’t everything

Many growers share the misguided belief that a greater wattage means a larger yield.  This is not necessarily true, light placement makes a big difference. Two 400W HID bulbs when placed side by side in a 1.5 metre grow tent will provide a better growing environment than one 1000W HID bulb. The light from a single bulb does not evenly spread throughout the entire growing area and as the light gets further from the bulb it is significantly weakened. The two 400W bulbs would produce a more even spread of light across all the plants and therefore a more evenly sized crop will develop as opposed to all the light being focussed on one plant in the middle, neglecting the rest which eventually causes them to become runts.


In conclusion

If you can afford the upfront cost of LED’s they will pay themselves off in the long run.  If not you’re best of going with High Intensity Discharge lighting systems with either Metal Halide or High Pressure Sodium bulbs.

There are many other lighting systems available but these tend to have a poor light spectrum or a very heavy price tag. HID, MH and HPS sodium bulbs are tried and tested and have been producing impressive yields since the very beginning of indoor marijuana cultivation and are sure to be around for a long time yet. However the future lies with LED’s!

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