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what lights are needed for growing weed

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.

Power equals poundage, so if you want big yields you’ll need more wattage. Professional LEDs can start at as little as 200 watts, and go up from there. A high-watt light can double the work of several low-watt bulbs.

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

Grow lights allow you to control exactly how much light your plants receive, ensuring they get the same amount of light day after day, without the grower having to solve problems with bad weather or cloudy days that happen in an outdoor environment.

Best CFL grow light brands

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.

As with HIDs, you can find CFLs at any local grow shop.

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.


Consider how often you’ll be growing weed and how long it will take to pay off the initial investment—if you grow once a year, it’ll take a lot longer to pay off an expensive light than if you grow multiple harvests a year.

Here are a few different CFL grow lights at different price points.

What lights are needed for growing weed

● Some manufacturers make dubious claims as to the strength of their lighting.

The uninitiated may believe that house lights are sufficient for cannabis plants. However, even if you use LED lighting, it is almost certainly too weak to help a marijuana crop in a grow room. Remember, your home’s lights are designed for your eyes rather than plants. The light spectrum required to help us see is very different from what plants require for photosynthesis.

Growth Cycle Stage

Furthermore, fluorescent lights don’t need the investment of an additional setup like with HID. You also don’t need to include a particular ventilation system to keep the room’s temperature down.

Why Should I Use Indoor Marijuana Grow Lights?

● Only useful for small grows.

What lights are needed for growing weed

When it comes to building an ROI comparing LED versus HPS be careful with results that are supplied by manufacturers of only one type of light source. I have seen manufacturers on both sides of the argument manipulate numbers to favor their specific light source. Below is an outline of things to look out for when receiving an ROI comparing lighting technologies:

After veg and moving to flower, most growers also agree that switching to a light source with more of the red spectrum is better for flowering. The old standard has been to use either CMH or fluorescents in veg and switch to HPS into flower. This is the tried and true lighting recipe for indoor cannabis growers. By far the majority of cannabis produced in North America today is grown in this way. With the onslaught of LED lighting manufacturers jumping into this new “green rush” of opportunities we are seeing this standard lighting recipe being challenged more and more.

What about growing in a greenhouse? From our graph above showing the spectrum of sunlight compared to that used for photosynthesis is there any benefit for using a light source where you can dial in the spectrum to add more blue? The natural light received by your crop in a greenhouse will cover all of your light spectrum needs. So the big question for greenhouse grows should center more around the ROI comparisons between LED and HPS — not about light spectrum needs. This is not something you will hear from light manufacturers of LED lighting. Your LED-only supplier will have you believe you NEED their spectrum specifically!

Determining ROI between LED and HPS

There is a lot of information out there on the internet from various growers and lighting suppliers. You can find a contradiction to almost every point you find! Most growers agree that for young plants through the veg stage of growth you will want to have a light source with a good amount of blue light or even white (full spectrum) lighting. The main reason for this is to reduce internode stretching to produce a stockier, healthier plant.

One of the reasons you still hear people claiming that LED is not ready for commercial cannabis grows is because the reflectors from an HPS fixture mounted 4 ft from the canopy will provide a wide angle of light so the crop will receive light from the fixture directly above as well as the lights from the next row over and even 2-3 rows away. This light is coming in from different angles hitting the crop beneath the canopy leaves that are causing shadows from the light above. This does not happen if you are using an LED fixture that is a big panel of LEDs or made up of multiple LED bars where they have to be mounted 9-12 inches from the canopy. You get no crossover from the fixtures but only shadowing from the top of the canopy.

Lighting and Cannabis Qualities

The best advice I have is to get a comparison of your ROI done by a versatile company. One that can offer both technologies where you can have light plans designed to the same levels with both technologies. Don’t trust just what the LED guy says or the only HPS guy says. Look at both, do your own math. Know what works for the strains you are growing and measure your own ROI. The easiest way to do this is going to this link and ask your local PL Light Territory Manager for advice as we are the “Lighting Knowledge Company” and whether you decide to use LED or HPS, you will get a true and honest comparison of both technologies.

The bottom line that I can share with you, from my perspective where I get visibility to lots of opinions on the topic, see lots of sales and growth cycles, talk to lots of growers, is this: We are still in the investigative and development stage with LED technology in this sector.