As with HIDs, you can find CFLs at any local grow shop.
The typical homegrower will only need one or two lights. Most states limit grow amounts to 6 or 12 plants, and one or two lights should be plenty for that. If you plan on running two separate rooms, one for vegetative plants and one for flowering plants, you’ll need two lights.
Aside from the price of the actual light, also take into account utilities—all lights will add to your electricity bill every month, but some more than others. High-intensity discharge lights—known as “HIDs”—may be cheaper to buy but can gobble up electricity, whereas LEDs are more efficient and kinder on your electricity bill but usually more expensive to buy.
LEDs also typically run a lot cooler than HIDs, so you may not need extra equipment to cool down your grow space, and one LED can usually be used for both vegetative and flowering growth. Some high-end LEDs allow you to change the spectrum for each growth stage.
CFL lights for growing 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.
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.
LEDs (light emitting diodes) are relatively new to the cannabis growing world, compared to HPSs, MHs, and CFLs, but they are quickly proving to be the way of the future. LEDs may be more expensive to buy initially, but they are far more efficient and kinder to the environment and your electricity bill. Some cities even give tax breaks to commercial growers who install or switch to LEDs because they’re better for the environment.
Other considerations when choosing a cannabis grow light
These bulbs contain mercury and metal halides, produce a blueish light, and are commonly used for vegetative growth. They require a ballast to regulate the current. In the past, ballasts have been big and bulky, but digital ones are now available.
Here are a few different HID grow lights at different price points.
Here are those same plants at week 6 of flowering under the ES300 LEDs
In our growing forum, many members have experimented with different grow lights for growing cannabis. Over the last few months, it has become apparent that one of the most popular brands for LED grow lights is an emerging company known as “ViparSpectra.”
Cannabis plants grown under the L600 Kind LED grow light
Which LED grow light brands can be trusted?
How Far to Keep from Plants: 36” away in vegetative stage, 18″ away in flowering
While Kind LEDs offer several additional models of LED grow lights, because of the price tag on these lamps I’m only listing the ones I’ve seen used by actual cannabis growers, though I’m sure the other ones are likely just as good. That being said, the following models have been proven to work really well for growing cannabis!
3 Main Types of LED Grow Lights
Grow Space: Up to 6′ x 6′ in the vegetative stage. Between 4′ x 4′ to 4.5′ x 4.5′ in the flowering stage.
With LED grow lights, you will generally get better results with many smaller LED panels, as opposed to a few big LED panels. For example, you will often get better results with 2 x 125W LEDs (total 250W) than you would with a single LED model that produces 250W. This is because more panels often make it easier for you to spread the light to where it’s needed.