Step 2: Choose Your Grow Light – What kind of light do you need to grow cannabis successfully?

The Sun

When you’re growing with the sun, you need to make sure that your plants are getting at least 8+ hours of direct sunlight each day for the best results.

It’s best that your plants get direct sunlight from at least 10am-4pm, and more light is better. Because of the high light needs of the cannabis plant (it needs more light than many other types of plants), it is not well suited to growing in a window (though I’ve seen plenty of growers start their seeds in sunny windows before moving their plants to a more suitable final location).

Household Lighting: Compact Fluorescent Light Bulbs (CFLs) & Household LEDs

Compact Fluorescent Light Bulbs (CFLs) & household LEDs are what people commonly use to light up their homes. They aren’t really made for growing plants, but can be a good way to get your feet wet in the growing world without a significant investment. They lack the power of dedicated grow lights, but can get the job done. CFLs and home LEDs like these are dirt cheap, and you can usually buy them from any big-box store without arousing suspicion. In fact, growing with CFLs is what I did for my first grow and I got them from a local Home Depot. I imagine that my first grow would’ve ended the same (or even better) had I used small household LEDs instead of CFLs, though they weren’t available back then. 

Other Fluorescent Lighting (T5/T8)

These lights are traditionally made for seedlings and plants that need lower light intensity than cannabis. If you do get other fluorescent lighting, I recommend sticking with a High-Output T5 light since they are the brightest option in this group. Even so, I generally recommend changing to stronger grow lights for the cannabis flowering stage unless you do major plant training (to keep plants very short) since these lights have a short light brightness range and must be kept very close to the tops of your plants. 

LEC (CMH) grow lights

LEC (Light Emitting Ceramic) is a brand name for a type of light (CMH – Ceramic Metal Halide) that has existed for quite a while. This type of light has come back into vogue after some rebranding, partly because it has some very positive traits for growing cannabis compared to HPS lighting. For one, LECs have a more natural color that makes it easier to care for and diagnose plant problems. Plus, it’s a lot better for security to have a light that doesn’t scream “WEED GROWING HERE!” like the unearthly yellow hue of an HPS. They produce significant levels of UV light, which can possibly increase trichome production. Additionally, they don’t seem to emit EMI (Electro Magnetic Interference) as much as their noisy HPS cousins which means you’re less likely to have a HAM radio enthusiast accidentally tracking down your grow. The plants grew surprisingly fast under a 315 LEC and we were impressed by the yields we achieved on our first grow.

LED grow lights

aLEDs are much more powerful than CFLs or any other fluorescent lighting. They are top-tier grow lights on par with HID lighting (HPS, LEC) when it comes to how much bud they can produce. They’re visually attractive and tend to be more appealing to growers because they’re not as ‘old-fashioned’ (though they tend to cost more). In fact, LEDs are the only grow lights that have seen major technological research and development in the past 10 years.

LED grow lights work great for growing cannabis and some companies have been refining their models for years (the combination of parts is almost like a company’s recipe). Each LED model is different and needs to be kept a different distance away from your plants. It can sometimes be hard to find any “standard” advice about growing with LEDs, yet these days there are quite a few brands which are well-tested and trusted by cannabis growers and these brands tend to have good support for questions. When in doubt, it’s always a good idea to just ask the manufacturer about how far away the lights should be kept, as that’s where new growers are most likely to mess up.

Metal Halide (MH) & High-Pressure Sodium (HPS)

MH/HPS grow lights (like the light pictured here) are a type of “HID” light like LECs. A combination of MH/HPS is what most commercial growers use when growing cannabis indoors. They are surprisingly cheap to buy and set up, especially considering how incredibly powerful they are.

HID lights work very well for growing cannabis and produce consistently good results indoors. However, the higher wattage HID lights tend to run hot and can leave a big mark on your electricity bill. You definitely want to make sure you’re getting the exact right lights for your space so you don’t pay for more light than you really need. HID lighting (HPS in particular) has another problem in that it’s been less popular over the last few years. This has made it increasingly difficult to find quality models if you’re not looking for a huge 1000W.

That being said, the smaller MH/HPS grow lights are actually really well suited to a small grow and don’t produce nearly as much heat as their bigger cousins. Check out a grow under a 250W HPS in a 2’x4’x5′ tent. I didn’t even use an exhaust!

See another grow under the same 250W light (with autoflowers), and yet another grow we did with 2 plants under a 600W HID grow light a while back.