Grow Lights Comparison

It’s inevitable: once you begin growing Cannabis, you’ll eventually wade into the controversial debate of which grow light is best. Factions on each end claim their preferred lighting method produces more cannabis buds than all other options. Join us as we talk about tried and tested grow lights.

When I first started growing, I made the mistake of looking into articles that boldly declared a winner between grow lights. It’s not that these weren’t helpful, it’s that some lights work well in one scenario and not so well at another.

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Written By Roy Stevens

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Quick Answer

“I’ve grown in just about every temperature imaginable. I’ve grown in humid summer conditions in unventilated attics and sub-zero winters in un-insulated out-houses. Although other vital aspects come into play when it comes to grow room temperature, lighting choice can make or break your operation. The choice of what grow light to use in your set-up is yours. Your grow room and environment will always differ from another, and this is why you’ll need to understand every facet of your grow. Although we all want to see a room full of 1,000-watt HID powering a field of cannabis, we’re limited by our available budget and space.”

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Grow Light Breakdown

The various growth stages of plants require different intensities of light, and each of the lights that we’re going to cover in this article all has different power outputs and wavelengths.

It’s for these reasons that we’re discussing the pros and cons of each light so that you’re equipped with a well-rounded education so you can make the best choice on your own.

It’s essential for us to note that each and every grow room will be different. This is why we can say that there is no “ultimate” setup, but only appropriate lighting.

It’s your job to adequately determine a few factors before you begin searching for the best grow light, whether it be Metal Halide, HPS, LED or CFL bulbs.

Are you growing in a grow tent or in a warehouse? Although these two examples are polar opposites, they still ask the same question. The space of your grow room will significantly impact your decision on which lights to purchase.

When growing in an 8’x8’ grow tent, your initial thought shouldn’t be to go for the power-saving CFL bulbs. Although CFLs are incredibly economical and emit little heat, they’re inadequate to cover the footprint required in an 8’x8’ grow tent.

Instead, a decision between metal halide and high-pressure sodium should be considered, and especially the wattage of the bulb. The higher the wattage, the higher the hood can be placed, therefore increasing the available light footprint. Of course, with each inch raised, the lumens emitted will have a diminishing effect.

The types of plants that you decide to grow are also going to impact your lighting choice. Growing a 6’ Cannabis sativa strain? Well then, depending on the available height in your grow room, you may be better off with a flat lighting system such as LEDs.

If you decide to super-crop an already-bushy Cannabis Indica strain, then you’ll need the most extensive lumen footprint available. This may be in the form of a high-intensity discharge (HID) light, such as metal halide or high-pressure sodium.

Maybe you’ve decided to keep your cannabis plants small, but pack as many into your grow room with the Sea of Green (SOG) technique.

Since canopy height should be uniform and the apical portion of the plant is where you’re focusing all the light on, then a LED system or even CFL lights could do the trick.

I’ve grown in just about every temperature imaginable. I’ve grown in humid summer conditions in unventilated attics and sub-zero winters in un-insulated out-houses. Although other vital aspects come into play when it comes to grow room temperature, lighting choice can make or break your operation.

When growing in an already hot environment, a 1,000-watt HPS grow lamp just isn’t feasible. Nor is a set of 600-watt MH. What is reasonable is a low heat-emitting light such as CFLs and LEDs.

These efficient systems will still pump out lumens while simultaneously having little effect on the overall temperature of the grow room.

When growing in a frigid environment, low-heat emitting lights are not the best option because your plants will become affected by the cold temperature.

This is the case where a 1,000-watt HPS will come in handy, and effectively raise the overall temperature while shining vital lumens directly at your plants.

When it comes to growing indoors, there are a few tried and tested grow light systems you can’t go wrong with.

Metal Halide (MH)

Metal halide is a HID style grow light. It comes in a wide range of wattages, from 250 to 1,000. MHs have been used in growing cannabis because they emit a strong blue wavelength, which helps the vegetative phase of growth.

Studies have shown that the blue wavelength in light increases the overall growth of plants.

Since MHs generate so much power, they require a separate ballast to safely send the required lumens to it. These ballasts are either magnetic or digital, and they can weigh upwards to 30 pounds each.

High-Pressure Sodium (HPS)

HPS is also a HID style grow light. These lights also range from 250-1,000-watts. HPS lights are known for their red and orange wavelength that is meant to increase the overall size of buds and speed up the transition from the vegetative phase to the flowering stage.

HPS is used to mimic the natural response in cannabis plants to react to the suns’ position when it’s on the horizon. This red wavelength triggers an internal response to begin flowering due to shorter days ahead.

LEDS (Light Emitting Diode)

LED grow lights have gained in popularity due to their low heat emission and custom wavelength configuration. This means that it’s possible to place red, white, and blue diodes to give a full spectrum of light to your plants.

In their early days, LEDs were seen as low-wattage alternatives to HPS and MH. Now, LEDs pack a serious punch and are seen in various power outputs as high as 1,000-watts.

LEDs also offer dimming options and include a “night mode” that mimics the light wavelengths of the moon. Some even come equipped with green diodes so you can check on your plants during the night cycle without doing any significant harm.

CFL (Compact Fluorescent Lights)

CFLs are perfect alternatives to power-hungry LEDs and HIDs. These are also routinely found in hardware shops at an affordable price. Not only are they easy to find, but they are also easy to set up without the need of having to deal with an external ballast. The heat that CFLs emit is negligible, and they are ideal when a grow room space is difficult to cool down.

Cannabis undergoes various stages between its initial germination and future harvest. Each light has a pro and con for these different stages.

Grow Lights for Different Plant Stages

Seedling Stage

From the point of germination, seedlings are at there most vulnerable during their initial growth into juvenile cannabis plants. Too intense lighting impacts them negatively, as they don’t have the foundation to support such bright light.

CFLs (T5 grow lights) are ideal for this stage because they can be placed nearly right above the seedling cotyledons without burning them. This keeps the seedlings short, and not leggy by stretching for the light.

LEDs can also be ideal for this stage of growth because of their full-spectrum capabilities and dimming options. Their low heat emission also allows them to be placed above your precious seedlings without harming them.

HIDs, such as HPS and MH are both not as ideal for seedlings as they are during the later stages of growth. These high-watt lamps would need to placed rather high from the canopy to not do any damage, and even if they have a dimming option, they will still need to be a fair distance away.

HIDs tend to be kept in the closet until the later stages of growth when the plant has enough leaves that can actually benefit from the high light output.

Vegetative Stage

This stage includes juveniles that have at least 3 nodes. The vegetative stage is an integral part of the cannabis plants’ lifecycle since it lays the overall foundation. The leaves grow, and the root system expands, and the photosynthesis required from the lights is as crucial as ever.

HID Lighting System (Vegetative Stage)
HIDs, such as HPS and MH are great for this stage if you’re looking for efficiency. The growth rates increase with the added watts from HIDs, and the dimming option can come into use at this point.

On the other hand, since the vegetative stage requires 18 hours or more of light, the power from HIDs will mean a massive electricity bill. Some claim that MHs are better than HPS during the vegetative stage because of their blue and white wavelength.

According to studies, the blue wavelength is associated with summer light, when cannabis naturally grows during its vegetative phase. This makes using MH over HPS more appealing.

LED Lighting System (Vegetative Stage)

LEDs might be the most ideally suited for the vegetative stage because of minimal heat and electricity costs. The long periods of light required to make for this efficient system to shine.

CFL Lighting System (Vegetative Stage)

CFLs work well during the juvenile stage of growth, but as the plant grows and demands more light, CFLs underperform in stimulating new and vigorous leaf growth. Their low-wattage will keep your electricity bill in the green, but their overall lack of intensity will keep your plants craving more.

Flowering Stage

This is the stage every grower waits for. Although all previous stages contribute to the overall flowering stage, it’s essential to make the best environment possible for a bountiful harvest.

HID Lighting System (Flowering Stage)

HIDs are potentially the best lighting method for this stage. Studies show that cannabis reacts better to the red and orange wavelength of HPS because it mimics the sun during its transition to the Fall season.

Fall is associated with a lower sun on the horizon due to shorter days, and cannabis naturally flowers at this point to make sure it becomes pollinated. This rush for pollination forces the female cannabis plant to push out ever more pistils to find pollen. Since we grow cannabis with only female flowers, they increase in size giving us the big buds we seek.

The disadvantage of HIDs in general, whether MH or HPS, is a large amount of heat they produce. The growing buds are vulnerable, and increased heat stress can diminish their yield. MHs can still be used with excellent results, but there may or may not be a significant difference in bud production. Regardless of HID choice, these wattage-machines won’t fail to yield abundant and resinous buds.

LED Lighting System (Flowering Stage)

LEDs can optimally be used during the flowering stage. Since many LEDs are digitally variable, users can select an all red diode spectrum. This flexibility from blue to red without having to buy additional bulbs may be a game changer for those on a budget.

LEDs are capable of yielding similar harvests to that of HIDs. This is generally the case when the grower is exceptionally experienced because the lower wattages from LEDs tend to create medium sized harvests.

CFL Lighting System (Flowering Stage)

CFLs have been and can be used during the flowering stage. They are not as ideal as the other lighting methods because of their low-wattage to efficiently cover the plant’s many bud sites.

Since CFLs have a harder time reaching bud sites throughout the plant, the yields are significantly smaller compared to the other options.

Ease of Use: Which Grow Light is Best?

The ability for beginners to set up is critical when deciding which light to buy.

HID Lighting System

HPS and MH are generally straightforward to use. Their main issue is that they have an external ballast that weights a lot and can make noise.

From this perspective, it’s not ideal for a complete beginner to try setting up their own HID system. HID systems usually require a hood as well, adding to the cost and increasing the setup time.

Professional growers bolt a large number of ballasts to a wall, keeping their wiring components absolutely organized and free of debris. This is what it takes to use HIDs because if they are left in an unprofessional manner, they can cause a disastrous fire.

LED Lighting System

LEDs are plug and play. That means that these are incredibly user-friendly and intuitive. They don’t require a separate hood and are relatively lightweight. Their onboard timer and digital menu make using LEDs extremely simple.

LEDs are the best option for beginners because they don’t require a large amount of knowledge from the user. All that’s needed is a place to hang it and plug it into a power source. It doesn’t get much more straightforward than this.

CFL Lighting System

CFLs are very simple in nature, but they require you to hang them up yourself. Grow shops sell hoods made especially for CFLs, but these can be costly. Growers wishing to cut their electricity costs down by using CFLs will need to build their own CFL housing unit.

Since CFLs is just the light, they don’t have a control system to power them on and off, which means you’ll need to purchase an external timer as well, thus increasing the know-how regarding this equipment.

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