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how many grow lights do i need for weed

HID (high-intensity discharge) is an umbrella term under which MH and HPS bulbs fall, which we’ll discuss more below. These types of lamps have a hood that reflects light and bulbs that are enclosed capsules containing a gas, as opposed to bulbs you’d find in your house, which have a filament that heats up.

Lights have fixtures and bulbs, and some require a ballast. Depending on the type and model, the bulbs or the fixtures can be more expensive. There are a lot of abbreviations, but don’t be alarmed.

Another consideration with cost is that some lights run hotter than others—HIDs, for example—so they may require additional fans or an AC unit to cool down a grow space. Extra equipment means more electricity, also driving up your utility bill.

Types of marijuana grow lights

You can find HID reflector hoods, as well as MH and HPS bulbs at any local grow shop.

However, because of their low price, if you’re new to indoor growing and not sure how often you’ll do it, you may want to invest in an inexpensive HID light at first to test the water.


New LED grow lights come out all the time, but knockoffs abound. There are a lot of cheap LEDs that don’t produce the right spectrum of light for plants.

Ventilation is also a concern. If you’re growing in a tight space with a light that runs hot, you’ll need to have fans in there, which also take up space. If there’s not enough room for a light and a fan, you may need to invest in a light that doesn’t run as hot, such as an LED. For example, grow tents are usually built tall to allow room for equipment up top, not to grow plants all the way to the ceiling.

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How many grow lights do i need for weed

The simplest way to determine the horticultural lighting requirements for a commercial garden is to think in terms of watts (W) per square foot of space. The typical high-performance indoor garden will provide 40-50W of artificial light per square foot of garden space. It is important to remember that we are talking about actual garden space, not the total square footage of the room.

Top feed systems with trays or troughs are easiest to automate on a large scale. Still, while stone wool is commonly used by large-scale commercial growers using this type of system, any soilless medium can be used just as effectively with a top feed set-up.

In many ways, the choice of medium and growing system comes down to the grower’s personal preference. Just about any growing medium can be used successfully. However, when gardening on a large scale, logistics—including disposal of the medium—should be considered.

Induction lighting systems and LED are more efficient at converting electricity into photosynthetically active radiation (PAR), which means they can provide the same usable energy as other technologies while consuming less electricity. That being said, intensity is crucial to the development of large fruits or flowers, which is why HIDs still remain the most popular choice for large-scale commercial gardens.

Assuming your 17,000-square-foot facility will be filled wall-to-wall with plants, you should plan on providing a minimum of 680,000W of light (for example, you could use 680 1,000W HID lighting systems). You could possibly reduce the total wattage required if you are using induction or LED lighting systems in place of HID lighting systems.

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How long the plants are kept in the vegetative stage depends completely on how large you want them before initiating the flowering cycle. For most indoor growers, the desired size can be achieved in three to four weeks of vegetative growth.

First, when setting up a commercial growing facility, remember that automation is your best friend. The more equipment in the garden that can be automated, the better. This automation will, in turn, reduce the amount of work that you must do.

How many grow lights do i need for weed

There are lots of options for grow lights that work well for growing cannabis indoors but in the end they boil down to 3 major types:

T5 Grow Lights

Note 2: Incandescent light bulbs (old fashioned light bulbs) are NOT suitable for growing marijuana!