Types of Indoor Grow Lights for Growing Marijuana

Light is super critical to getting high quality buds from your cannabis plants. If you’re planning to grow indoors, then what you want is to get the best kind of lighting for your setup. As you may have noticed, there are quite a few choices when it comes to indoor growing lights and as you might have guessed, each has its own pros and cons. How do you know which one to get?

The importance of light in growing marijuana

We all know that most plants, especially cannabis, need lots of light to grow. While sunlight is still the best kind of light for your marijuana since it is more powerful and has an equal distribution of the different wavelengths that plants have evolved to use, that is typically not an option when home growing in the US since laws require growers to keep their plants away from public view. 

Although artificial lighting is not as good, it still does its job well. According to studies, higher light intensity can lead to bigger yields and more THC while adjusting the color temperature of  your lighting will affect your plant’s growth, morphology and metabolism. Studies have shown that using light towards the blue spectrum during the vegetative stage, and yellow to red spectrum during the flowering stage can give you the best results. 

Things to consider when shopping for grow lights

Most modern lighting can deliver as much light as you want for a price. However, the most expensive grow lights aren’t always the best. Rather, what you want is the most cost-efficient lighting for your setup. You would not want to spend on an Advanced Platinum Series P300 300w 12-band LED Grow Light just to grow two plants in a 2×2 tent. It might be nice, but ask yourself, would you be able to use it to the fullest so you can get your money’s worth? 

Here are a couple of things you should first consider when shopping for grow lamps:

  • The size of your growing area – you need to consider how high you need to fix the light so that it scatters effectively and not touch too closely to your plants, etc.
  • How many plants you’ll be growing – especially if you’re tending to multiple growing spaces where one space is dedicated for seedlings, another for plants in their vegetative stage and another for flowering ones, you may need to get more than one set of lights of different kinds
  • Your budget – remember that you won’t just be paying for the lights, but how much power they would consume overtime, how long their lifespan would be, how much it would cost to replace, etc
  • Your location – growers in cold places sometimes use HID to compensate for temperature drops. If you’re in a region that doesn’t get extreme temperature fluctuations, LED lights often work best. 

Kelvins, Wattage, Lumens

When shopping for grow lights, you will come across these units of measurements used to gauge the performance of each kind of lighting. 

Wattage and lumens often get confused with each other. It is important to know the difference between the two because these numbers will immediately tell you how much you’ll be spending on your lighting expenses. 

Watts – the amount of energy needed to produce a certain amount of light. 

Lumens – the amount of light a grow light gives off. 

Back then, older lights needed a lot of power to produce a lot of light which is why people used to equate wattage with light intensity. However, as technology improved, LED grow lights are now able to deliver more lumens per watt. One thing to note is that some lights are still rated in watts to denote their light output. For example, CFLs usually have two wattage ratings on their packaging. One of these is the actual wattage used by the bulb and the other is its equivalent output in comparison to an incandescent bulb. This means that a CFL that is as bright as a 100 watt bulb may only consume around 25 watts.

Meanwhile, Kelvin is the unit used to express the frequency spectrum of a grow light. A higher number does not mean better. Rather, If you want to know how light looks like at varying points of the spectrum, try adjusting the color temperature on your TV or computer monitor. 

Types of indoor growing lights

Experienced growers use all sorts of artificial lighting to squeeze out every drop of potential from their plants. They typically combine different types of lighting to balance energy consumption, heat, space, etc. but if you’re a home grower raising just a few plants, you don’t need to pore over too much on which type of light you need to get. Most likely, the grow tent kit that you’re looking to buy also comes with a grow light and that’s good enough to start with.

Grow lights sold nowadays come in all sorts of shapes and sizes but most, if not all, can be categorized as a compact fluorescent lamp (CFL), high-intensity discharge lamp (HID), or Light Emitting Diode (LED). Each comes with its own set of advantages and disadvantages but in general, what you want is to get the most yield out of your total lighting expenses. 

CFL

If you’re thinking of those long tubes typically seen in old houses, yes those are a kind of fluorescent lighting. Nowadays they come in smaller bulbs but the technology barely changed. CFL still uses a tube filled with argon and a small amount of mercury vapor. When electricity is introduced, these elements release UV light that excites the phosphor coating on the inside of the tube which then emits visible light.

CFL is not a kind of grow light known for delivering yields but it can still be used in certain setups where you need cheap lighting that you can put close to your plants. It can also be used as supplemental lighting or as lighting for seedlings.

Pros: 

  • Cheap. An average 130W equivalent CFL bulb is just around $12.
  • Doesn’t get hot. You can put it as close to your plant as you want without harming them.
  • Easily available.
  • Easy to set up.

Cons:

  • Weakest light output, won’t get you explosive growth and yield.
  • Relatively short lifespan. Average of around 6000 to 15,000 hours.

HID

HID’s are typically used as streetlights, stadium lighting, car headlights and other outdoor settings that need intense illumination. This used to be the gold standard for cannabis lighting but is slowly being eclipsed by LEDs.

Marijuana growers often use two kinds of HID grow lights: 

JoeX, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
  • Metal halide (MH) – uses a mixture of mercury and metal halide gas to produce intense white light. Typically used during the vegetative stage.
Plantlady223, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
  • High pressure sodium (HPS) –  uses pressurized aluminum oxide, sodium metal with mercury and several other elements. Produces a light with a distinct yellowish glow and is often used during the flowering stage.

Pros: 

  • Powerful light output that according to most growers produce the best yields.
  • Omnidirectional illumination if needed. Better light spread.
  • Can warm up a cold growing space.

Cons:

  • Gets hot and has to be installed at a greater height. Not ideal for small grow spaces.
  • Relatively expensive and not as widely available. A 150W HPS kit with 1 bulb costs around $85.95.
  • Uses toxic metals.
  • Consumes a lot of electricity. Costs a lot more to run compared to CFL and LED.
  • Color temperature is fairly limited. 
  • May need additional equipment like a ballast, reflector, etc.

LED

D-Kuru, CC BY-SA 3.0 AT https://creativecommons.org/licenses/by-sa/3.0/at/deed.en, via Wikimedia Commons

LED lighting is arguably the future since it is the most energy-efficient option. LED technology is also still maturing which means products are going to be cheaper and even more efficient in the future. LEDs produce light with very little heat by flowing electricity through semiconductive material like selenium or silicon.    

Pros: 

  • Produces the least amount of heat. Can even be used closely for lighting seedlings.
  • Most energy efficient. 
  • Can reproduce the needed color spectrum conducive for vegetative and flowering stages. 
  • Longest life compared to HID and CFL.
  • Easy to set up, even for beginners. Does not need additional equipment like HIDs.

Cons:

  • High initial cost. 
  • Has yet to beat HIDs in terms of yield.

Frequently Asked Questions

What are LED grow lights?

Light-emitting diode or LEDs are a very cost-efficient type of light that is now being widely used for indoor growing setups. LED lights last significantly longer and has a higher lumen output for a fraction of power needed by other types of grow lamps.

What is MH, HPS, or HID grow lights?

HIDs or high-intensity discharge lamps are often used in settings where intense omnidirectional illumination is needed. Metal halide (MH) and high-pressure sodium (HPS) lamps are kinds of HID lighting. HID is considered by many as the gold standard for marijuana growing.

Can CFL be used to grow marijuana?

It is possible to grow marijuana using compact fluorescent lamps for growing marijuana. However, CFLs do not provide the best kind of light for growing which make them somewhat cost-inefficient.

Conclusion

While HID lights still produce the best results for now, the growing number of advantages associated with LED grow lights is converting more and more growers, especially those cultivating indoors at home. The high initial cost seems negligible given the energy savings to be had in the long run. Given this, if your focus is growing the biggest and best buds and you have growing space to spare, go with HID lights. If you’re a new grower looking for indoor grow lights that’s easy to set up and can be used for a long time at any growing stage, you can’t go wrong with LED lights.

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