Grow Lights for Weed: A Comprehensive Guide

grow lights for weed

So, there you are, getting ready to grow your own green medication. Your sincere joy and excitement are overflowing. But as soon as you begin assembling your growing equipment, your head’s on fire. Gradually, exhaustion and confusion, sprinkled with annoyance replace the initial waves of euphoria.

We feel you, bud buddies, and we’ve been there before. We believe that sharing means caring, and that’s why we’ve compiled a comprehensive guide for grow lights for weed (when we say comprehensive, we mean it).

We won’t be bombarding you with all those complex terms we used to face back in science class.

Instead, we will focus on the things that truly matter to you as a cannabis grower in order to understand which grow lights for weed will work best for you. So put that bright smile on your face and join us below.

Grow Lights for Weed: The Basics

LED Cannabis Grow Lights

Marijuana is called weed for a reason. Marijuana plants are determined to grow, develop, and survive just like any other type of weed in nature – robustly, vigorously, and unstoppable.

Growing weed outdoors and indoors has both pros and cons. But with outdoor cannabis growing there are not that many sci-fi mission-like terms and setups when it comes to the equipment you need.

Growing outdoors, weed relies heavily on the best conditions that Mother Nature can provide when it comes to a gentle breeze, fertile soil, and plenty of sunlight.

With indoor cannabis growing, you are the one who gets to mimic some of the most important factors related to the well-being of your marijuana plants – consistent air flow, as well as reliable and consistent access to light, among others.

Grow lights for weed are your weapon for mimicking the natural sunlight.

The sun triggers flowering as the days start to get shorter, signalizing the plants that the autumn is approaching. But what’s more, sunlight comes in different colors which make up the color spectrum of the light. This spectrum is invisible to human beings.

However, plants not only perceive the different colors of the light clearly but they also use the different colors differently during different periods of their lifespan to accomplish various complex reactions, blooming included (and we can’t be indifferent to that).
In order to produce healthy stems and leaves, weed requires plenty of light from the blue spectrum. In order to nurture the flowers and turn them into juicy buds, weed requires plenty of light from the red spectrum.

What light spectrum does weed need to grow? by the Indica Institute

That’s why you can’t possibly opt for whatever type of lights for growing weed indoors successfully. Other essential factors include heat output, proper positioning of the lights, lumen, wattage, Kelvin, to name a few.

What you want to keep in mind is that grow lights = food for your marijuana plants. Better lights, better buds. It’s that simple.

Video by DIY2HIGH – More Light! More Bud!

You can’t afford to overlook the importance of grow lights for weed because lighting will affect both the quality, as well as the number of your crops. Plus, your choice of grow lights will affect your budget both short-term and long-term.

Your choice of lights will affect all the rest of the growing equipment you’ll need. For instance, high heat emitted by grow lights can be curbed by either investing in a reliable ventilation setup or by growing your plants in a rather vast, large space that won’t get overheated easily.

With this example, we also want to highlight the fact that every grower has unique needs and that’s why there is no short-cut, fit-them-all magical formula that can work wonders on its own.

Video by From Seed to Stoned – 3 Simple & Free Ways to Grow Bigger, Denser Buds! Cannabis Grow Guide Week 12

Compact Fluorescent Grow Lights (CFLs)

Compact fluorescent lights were originally created to replace the E26 Edison incandescent light bulb, which used to be the standard for most households. However, CFLs are designed to have a much longer life span than traditional incandescent lights while using significantly less electricity.

As a rule of thumb, incandescent bulbs can NOT be used for growing weed. The light emitted by incandescent bulbs is very low and insufficient for your cannabis plants, and it falls into the red side of the light spectrum. Meanwhile, it is even lower when it comes to emitting light that falls into the blue side of the light spectrum.

The only way you can take advantage of incandescent bulbs for growing weed is to use them in the early stages of nurturing your cuttings when working with marijuana clones.

Fluorescent lights are convenient to use, don’t emit so much heat as HID lights, they are effortless to install, and can be found in just about any local store, as well as online.

Setting up a fluorescent lighting system for growing weed won’t cost you a fortune in terms of the investment you make for your equipment. Also, it won’t cost you a fortune when electricity bills finally arrive.

However, it is exactly because of the low output that fluorescent lights are considered a poor light source for budding and flowering as compared to the much more powerful HID and LED lights.

But this rule has exceptions, too.

If you’re planning on a small-scale cannabis growing operation (approximately 3 marijuana plants), CFLs can actually do quite a decent job to suit your needs.

CFLs make a superior choice for beginner marijuana growers because they are way much easier to manage than HID lights. Plus, since they emit less heat than HIDs, CFLs will require a less complex ventilation setup for your grow room.

But as to the downsides of using CFLs, considering their low output, you need to keep in mind that you’ll end up with decreased yields as opposed to HID and LED lighting systems.

If CFLs appeal to your level of experience and personal needs when it comes to growing weed, then how can you choose the right ones?

For a start, the labels of CFL lights display different descriptions that refer to the specific color spectrum such as Warm White, Cool White, and Soft White, among others.

Some manufacturers rely on measuring the color temperature of light and listing the information regarding the color spectrum by using descriptions such as 3000K, 4000K, and 6400K, to name a few. The color rendering index is measured in Kelvin, and hence the 3000K-4000K-6400K specifications are provided by some manufacturers to indicate a lamp’s ability to show off individual colors of the color spectrum.

Video by LesnProToGo – White Balance & Kelvin Color temp explained

Understanding the color spectrum when choosing suitable CFL grow lights from seed to harvest is very important.

As a rule of thumb, the warmer the color of CFLs, the more of a yellowish tinge is emitted. The cooler the color of CFLs, the more of a blue tinge.

During vegetation, you need CFLs that lean on the blue side of the color spectrum, respectively, a Cool White CFL is what you’re looking for.Expressed in Kelvin, you want to opt for 6500K or 5000K.

A minimum of 16 hours of light is recommended indoor marijuana plants during vegetation.

During flowering, Warm White CFLs are your go-to, and you want to opt for lights labeled as 2700K – 3000K.

Marijuana plants transition to flowering when being introduced to 12 hours of undisturbed light vs. 12 hours of undisturbed darkness. Auto-flowering strains enter flowering automatically (no photoperiod).

In any case, make sure to avoid CFLs of 3500K and 4000K because the light emitted by these particular CFLs is not really useful for cannabis plants.

When it comes to wattage, 250W, 400W, and 600W CFLs work best.

However, you can feel free to use any combination of CFLs with different wattage, as long as the configuration suits your personal preferences. Whether you go for multiple CFLs of low wattage or fewer CFLs of higher wattage, you can still enjoy good yields. Just choose a configuration that suits your growing space, and of course, the type of configuration that will be the easiest to install and work with.

How to position CFLs

Keep in mind that regular re-positioning of your CFL grow lights will be absolutely necessary. This has both pros and cons and only you can determine whether the pros are more than the cons.

As a rule of thumb, you want to place the CFLs at approximately 2-4 inches away from your plants during any stage of their development.

If you place them too near, your plants won’t have the much-needed stimuli to reach towards the lighting source, so they will remain rather bushy, and this will also affect the number of buds you’ll harvest.

But if you place the lighting source too far away, your cannabis plants will start stretching too much, and this can result in tall and lanky plants. Elongated stems due to extra stretching are associated with the production of loose buds that are still useable but quite far away from being dank and heavy-weighting.

Most importantly, CFL grow lights will only benefit your marijuana growing mission when combined with a suitable reflector. Your growing space must be optimized to reflect the light emitted by CFLs, as CFLs won’t possibly cater to your marijuana plants’ lighting needs on their own.

Video by Everest Fernandez – Grow Light Reflectors 101 – Choose the Best Reflector for Your Indoor Garden

HID Grow Lights

Just the very mention of HID grow lights for weed is capable of giving veteran marijuana growers the goosebumps. Indeed, HIDs are the absolute cult-classics in terms of massive yields. Or at least HIDs used to be the only option capable of rewarding growers with such an amazing harvest before LED lights appeared on the global stage of cannabis cultivation.

HID grow lights is the abbreviation of High-Intensity Discharge. There are two major types of HID grow lights, namely High-Pressure Sodium (HPS) and Metal Halide (MH).( )

During vegetation, it is Metal Halide grow lights that can provide plenty of crisp lights from the Blue color spectrum to help your plants thrive.

During flowering, it is High-Pressure Sodium grow lights that can provide plenty of beneficial light from the red color spectrum to feed and fatten those juicy buds.

What makes HID lights superior to fluorescent lights for growing weed is the high lumen per watt ratio. That means HID lights emit a much stronger, crispier light as compared with fluorescent lights. And as we mentioned at the very beginning of this article, better lights = better buds.

Both HPS and MH grow lights come in different wattage. The wattage of HID lights that matters to you is 400W, 600W, and 1000W.

Generally, HID lights of 400W are perfect for growing up to 10 plants.

Depending on your growing space, as well as the growing techniques you will or will not apply, using several 600W HID bulbs can be better suited than using multiple 400W bulbs.

1000W HIDs are only recommended for professional and/or large-scale marijuana growing operations.

How to position HID grow lights?

For a start, you want to make sure that your HID grow lights will be easily adjustable at any time. You can either use a light stand or hang the lights by using chains and hooks.

Keeping in mind that marijuana plants can grow up to 1 inch within a single day, monitoring and re-positioning your grow lights regularly is a MUST. Or else, due to the high heat emitted by both Metal Halide and High-Pressure Sodium grow lights, your cannabis plants can get burnt more quickly than you actually expect.

A great method of testing whether the heat of your HID lighting system is suitable for your plants is to use the back of your hand.

Just place your hand under the grow lights. Does the heat feel too hot on your hand? Then it is too hot for your plants, too!

You can also use the average optimal light height recommendations given below. But do keep in mind that these are closely related to the power of your ventilation setup, as well as other essential factors that are unique to each grow. So use these as reference ONLY and don’t just blindly follow these guidelines. Keep monitoring your plants regularly because this is the only truly reliable method to make sure you won’t burn them.

For 400W Metal Halide grow lights, the optimal light height is approximately 1 foot away, while for 600W MH lights – 1.5 foot.

For seedlings, though, the recommended light height of Metal Halides is 2 feet.

For 400W High-Pressure Sodium grow lights, the optimal light height is approximately 1 foot, and 1.5 foot for 600W High-Pressure Sodium grow lights.

The average lifespan of an HPS bulb is about 18 000 hours. That’s an important factor to keep in mind, as once HPS bulbs “get old” they will start to draw away too much electricity than their actual wattage rating. This means your energy bills will grow even more while your plants won’t really benefit in terms of producing more yields. Meanwhile, the average lifespan of an MH bulb is about 9000 hours.

Video by Growing Exposed – HID Light Spacing – Growing Tips 05

In a nutshell, HIDs come with their benefits and downsides. Undoubtedly, HIDs are the tried and tested, old-but-oh-gold method for growing weed indoors with tremendous success.

But they are also difficult to install, have a high heat output (yes, HIDs can literally fry your plants), and they can pretty much suck away your hard-earned money when the electricity bill arrives.

HIDs seem to be the more budget-friendly option in terms of the first investment you make, and especially as opposed to the investment you’ll need to make for purchasing LED lights. But since HIDs will greatly increase your energy bill, it’s best to think twice.

Then again, there can be many exceptions to the pros and cons of HID lights because we grow weed differently. An indoor grower who starts his growing operation during the cold winter months can find HIDs to be more than perfectly tailored to help keep up the temperature within the grow room. Meanwhile, another grower who plans to start an indoor growing operation during the hot summer months might have a lot of trouble dealing with HIDs.

Heads Up: HID lights cannot possibly function without installing a reflector. Nevertheless, HID lights require a suitable ballast in order to operate. Basically, a ballast is merely a transformer.

But this transformer is extremely important for HID grow lights as it alters the electrical current used by the bulb. Most noteworthy, make sure to choose a suitable ballast for the type of bulbs you’re using, as the type of ballast must match the bulbs, or else, your HID lighting setup won’t function.

Pre-wired kits work best for the first time HID growers, unless you happen to be good with wiring and possess sufficient knowledge in dealing with electricity-related setups.

Quick Tip: Lighting Timer
A lighting timer can make a huge difference in the way you maintain the lighting schedules of your marijuana plants. It will allow you to have much more freedom as a cannabis grower. You will be able to automatically switch your grow lighting system on and off, depending on the stage of development your marijuana plants are currently in.

Fluorescent lighting usually works with any type of standard light duty grounded timer. HIDs do require a heavy duty timer, though, as they use much more power than fluorescent grow lights.

LED Grow Lights

LEDs are the newest members in the grow lights for weed family. And yes, being the most modern-day version of marijuana grow lights, LEDs come with unique advantages over both CFLs and HIDs.

#1 – LED lights have a low heat output. Since LEDs are low heat, you won’t have to fret that much about re-positioning your grow lights to avoid stressing, burning or mal-nurturing your cannabis plants. What’s more, it will be easier to control the temperature in your grow room.

As LEDs emit less heat than HIDs, keeping the temperature in your growing room between 80 – 85 degrees Fahrenheit is crucially important.

When it comes to humidity levels that are intricately connected to the temperature in your grow room, as well as your green ladies’ well-being, humidity should be kept at approximately 40% – 45%.

Don’t forget that these are all general recommendations as different marijuana strains have slightly different tolerance to temperature and humidity. That’s why choosing marijuana seeds or clones from a reputable retailer is the very basics of a successful growing operation. If you work with superior genetics, you can actually rely on the descriptions provided regarding each strain’s specifics.

#2 – LED lights provide the perfect color spectrum to cater to your marijuana plants’ needs during both vegetations, as well as flowering. So once installed, LED lights will prove to be suitable during the entire life span of your plants.

#3 – LED lights have the longest lifespan as compared to all the rest of the grow lights out there. In fact, the average lifespan of LEDs is estimated at 50 000 + hours, and that can make a huge difference in making your cannabis growing operation as low-maintenance as possible.

#4 – LED lights are extremely energy saving. To back this statement up with numbers, LEDs can save the stunning 80% from your energy bills, compared with HID lights.

A standard 90 Watt LED system uses as much electricity as a 400 Watt HID bulb, whether it comes to High-Pressure Sodium or Metal Halide HIDs.

You can see for yourself that based on these comparisons, LEDs make the most cost-effective solution. Plus, these properties make LEDs the greenest lighting system in terms of environmental-friendliness.

Do keep in mind, though, that LEDs are also much costlier than HIDs and CFLs when it comes to investing in your first LED lighting setup. You can expect to see a positive return on your investment within about 12 months after the initial purchase and subsequent exploitation of a LED light system for growing weed.

You want to make sure that the LEDs you opt for are of the highest quality. Any LED systems that seem temptingly inexpensive at first are highly likely to prove to be of low-quality. Low-quality LED lights won’t give you the results you’re aiming for when growing cannabis indoors, so don’t let yourself fall victim of scammers.

How to position LED lights?

During vegetation, LED lights should be placed at approximately 14 – 18 inches from your plants.

During flowering, LED lights should be placed at approximately 10 – 14 inches from your plants.

Of course, this is only a general recommendation because different growers will opt for LEDs of different wattage.

The wattage of the LED lighting system you choose will depend on the number of plants you plan to grow, as well as the dimensions of your growing space. Reputable retailers provide reliable information regarding the proper light height.

Now, what’s important to remember when using LEDs as your plants transition to flowering is to keep the light height intact before you start noticing the genuine bud formation.

Before the buds start forming, it’s counterproductive to place LEDs a lower as this is shown to stunt the development of the fragile buds. As a result, you can end up with decreased yields upon harvesting.

Video byNoCalGrow – LED vs 1000W Double-Ended HPS Medical Cannabis Grow Test

Heads Up:Although LEDs have a low heat output, that doesn’t mean you won’t need to invest in a reliable ventilation setup. Air exchange is crucial to prevent fungi and molds but it also helps to strengthen your plants. Only strong marijuana plants will be able to nurture massive, multiple buds.

As opposed to both HIDs and CFLs, LEDs do NOT require an additional reflector because they have a fixed angle which is created to direct the light output straight to your cannabis plants.

Grow Lights for Weed: Final Takeaways

When choosing the type of grow lights for weed that will work best for you, take into account all the possible pros and cons that truly matter to YOU.

What are your long-term goals as a cannabis grower? Which lights will be the most suitable ones based on your grow space unique specifications, as well as your current level of experience as a grower?

Are you looking for a budget-friendly, easy to install lighting setup without being bothered about decreased yields? Then CFLs can work great for you.

Are you looking into tried-and-tested lighting setups used by veteran marijuana growers from several generations? Are you on a mission of getting massive yields upon harvesting? Can you handle extra wiring and optimize excess heat efficiently? Then HIDs can prove to be your best choice.

Are you looking for an energy-saving lighting system that can still let you enjoy excellent yields? Do you want to avoid having to deal with excess heat in your grow room? Then LEDs can be a wonderful option to suit your needs.

You can also use a combination of CFLs during vegetation and HPS grow lights and/or LED lights during flowering. Many professional cannabis growers swear on the benefits of combining different grow lights to boost yield. So instead of letting yourself get overwhelmed, consider how blessed we are with all the various grow lights for weed nowadays. We feel lucky, and what about you?

Leave a Comment

Your email address will not be published.