Success Secrets Using LED Grow Lights for Marijuana Growing

Indoor marijuana growers have several grow op challenges, and perhaps the most important is what to use as an “indoor sun.”

Until LED grow lights came on the scene, almost all growers used high intensity discharge (HID) metal halide and high pressure sodium grow lights. HID bulbs were originally made for street lighting, store lighting and other non-horticultural purposes.

A few HID manufacturers claim to now be making HID bulbs with spectrums themed for marijuana’s light spectrum needs, but that doesn’t mean HID is the best choice for indoor grow rooms. Why? Because HID bulbs are energy wasters, too hot, and wear out fast. The huge amount of heat they generate costs you in extra air conditioning expense, and can burn or stunt plants and buds. They can also burn you.

HID problems are why more and more growers are switching to light-emitting diode (LED) grow lights. LED grow lights have many advantages over HID, including less heat, better electricity-to-light conversion ratios, longer unit life, adjustable spectrums, and reduced energy costs.

Avoiding Common LED Grow Lights Mistakes

The Growing Marijuana Perfectly team has eagerly embraced LED grow lights as many cannabis growers have. We’ve tested almost all the major brands (whose top units usually cost at least $1400 if not much more) and many minor brands too. Unfortunately, our conclusion is that many makes and models of LED grow lights are a rip-off in one way or the other, and that using LED grow lights requires you to make careful, specific adjustments in how you grow your plants.

If you want to avoid common LED grow lights mistakes and get the most bud weight and potency from your LEDs, here’s what you need to know about LED grow lights…

First of all, we’re not impressed by the majority of LED manufacturers. They make impressive-sounding product claims, but don’t have third-party, legitimate side-by-side marijuana grow op testing to prove their claims.

For example, some claim their lights will equal or even outperform HID grow lights (including double-ended) in harvest weight and cannabinoid/terpenoid percentages. But other than anecdotal reports from a few growers shown in promotional materials from the manufacturer, you never see definitive proof of this claim verified by scientific testing and third-party certification. Our research shows that only the most skilled growers using LED routinely get harvest weight and potency equaling what you get with high pressure sodium (especially double-ended HPS).

Another challenge using LED grow lights is you might have to adjust several feeding and environmental factors to accommodate LED grow lights’ effects on your marijuana plants, and there’s a learning curve involved, it’s not one size fits all. You have to be more attentive to your plants, and know that every marijuana strain has its own way of handling grow light spectrum and intensity.

Using LEDs, you may want to have your room be a few degrees warmer than usual, and add extra calcium and magnesium to your feed program, especially in bloom phase. Growers are familiar with Cal-Mag supplements already. Use a 50% reduced dose intermittently during grow phase, and every other watering during bloom phase.

You also pay closer attention to the amount of water and nutrients you give your plants because some LED lights increase water use by about 40%. We reduce the parts per million of our feed program in those scenarios, because running more water means running more nutrients, and that can cause nutrients burn and lockout.

LED-light-burn.jpgPerhaps the most common problem you see with LED grow lights is light burn, sometimes called leaf bleaching. Take a look at the photo above. That’s classic LED leaf burn. Your plants’ leaves, especially those in the top third of the canopy, become bleached out, turning a pale yellow and often becoming crispy, although the leaf veins stay green.

This bleaching problem is confusing because it can easily be misdiagnosed as a nutrients problem, leading to nutrients dosing mistakes and other hassles. Bleaching interferes with photosynthesis and other metabolic processes, and can sabotage plant growth, structure, potency, and harvest weight.

Most LED manufacturers aren’t honest about this problem. They give you canopy-to-light distances that are way closer than you can actually safely use—because they don’t want to scare you away from buying their gear, especially when you’re growing SCROG or in limited vertical height gardens. And when I say “limited vertical height,” I’m talking about grow rooms with eight-foot ceilings, which is what most home marijuana growers have.

Using the most powerful LED grow light models from most major LED manufacturers, we’ve had to put the lights at least 36-40 inches if not much higher away from the canopy to reduce bleaching. These are models that manufacturer’s advertisements claim will replace a 600-1000-watt HID light.

So using one of these high-powered LED lights in grow room with eight-foot ceilings, you’ve already lost three feet or more of grow height due to worries about bleaching– meaning your plants can’t be more than five feet tall, and that doesn’t include the inches you lose due to light stands, light movers and hangers. The sad fact is, some LED grow lights are just as bad as double-ended HID when it comes to canopy burn and how high you have to have them above the canopy.

Even using LED grow lights that allow adjustable spectrum and intensity, we’ve still seen bleaching after dialing down the intensity by 50%. Experts we’ve spoken to say the bleaching isn’t due to intensity alone, it’s also due to the manufacturer choosing the wrong spectrum output.

Another problem is some LED grow lights manufacturers overestimate their lights’ “footprints.” The light footprint is how much of your grow room canopy the light is alleged to provide adequate light for. We’ve tested lights that manufacturers said provide adequate photon intensity for 16 square feet, but the actual coverage was 12-15 square feet. Some manufacturers give differential coverage estimates for grow and bloom phase, but what we’ve experienced in multiple grows with different brands of LED is that coverage estimates are often about 5-30% too generous.

Yet another hassle for LED grow light users is getting useful technical support and warranty repair and replacement. Many LED grow light manufacturers treat growers disrespectfully. For example, here’s a typical complaint posted online about Fluence Bioengineering, an Austin, Texas LED maker that’s one of the so-called “most respected” LED grow light manufacturers:

“Fluence customer service is non-existent. If you do get ahold of someone they say they will call you back with info but never do. After 5 calls, over an hour on hold and a 40$ long distance charge I was finally able to order a light. Asked the sales guy how long it takes until they ship and he said about a week after payment is cleared. Took a week to clear payment and two weeks after cleared payment I called to see if it was shipped and they said it will take another 15 days until they will ship it. I have now been waiting almost 2 months. If you do order a light don’t expect it any time soon. Can’t imagine what it would be like to try and get warranty or if you wanted to order multiple lights.”

This is just one of many negative reviews about Fluence, and it doesn’t surprise us, because when we had problems with Fluence grow lights and contacted the company, it was impossible to reach Fluence tech support, customer service or management. This kind of rude stonewalling is also with seen with some other LED manufacturers.

Companies like Fluence ought to realize that Chinese LED grow light and Osram LED chip counterfeiters are coming for them soon. We used black-market gear backchannels to procure Chinese-made LED grow light counterfeits that technically appeared to be the exact same as the lights they were copying. The Chinese even claim to have figured out a way to duplicate Osram and Cree LED chips (Osram and Cree are the purported industry standard in LED chips).

These Chinese units cost at least 40% less than the original brand’s units they’ve duplicated, and seem to perform just as well. Problem is, when these units go bad, the Chinese seller isn’t available for tech support or warranties.

We could go on and on about the nuances of different LED grow light design, purposing, warranties, pricing, and performance. When you start trying to understand these nuances, you quickly discover that it’s a technical rabbit hole you go down and you might never come out again.

To make things simpler for you, our team has agreed that we can vouch for the integrity of at least three LED manufacturers. We’ve personally tested lights from two of the three, and have interviewed all three.

One company we have faith in is California Lightworks. Their CLW 1100 is used in dozens of profitable commercial grow ops, and they have smaller models that work well in home grow ops. Their technical support and warranty people are timely, honest and professional.

Another company with integrity and useful gear is NextLight. They only offer three lights, and one of their lights (the Mega), is equivalent to a double-ended HID HPS, so you need high ceilings and/or very short plants to use it.

NextLight is intriguing, because they’ve chosen a pure white color spectrum. This contrasts sharply with the spectral choices of most other LED manufacturers, whose lights spike up at specific parts of the visible light wavelength range. We’re in the process of procuring a NextLight for testing, and will let you know the results, but commercial grower friends of ours who are using the NextLight Mega report good results.

The third company we recommend is Lush Lighting. Lush owner Matt Johnson spent years researching photons, electrical engineering, grow lights, and cannabis photochemisty before he designed his grow lights.

When you talk to Matt about why his lights outperform brands that cost more and are better-known, he launches into a lengthy discourse about xanthophyll, carotenes, phycobilin proteins, photon flux, and other complex topics.

I don’t pretend to understand all the science he explains, but I trust his expertise because his lights have consistently been the most useful LED grow lights in my grow ops.

In some ways, Matt’s lights are “old-school” in that they have no dimmers, Bluetooth capability, controllers or other fancy and often unnecessary features that have shown up on some premium LED grow lights in the last ten years.  And compared to newer, more expensive LED grow lights, his are often heavier, hotter and noisier.

But whatever old-school features Lush LED lights might have, they do the job well, and Matt’s company is refreshingly helpful and has a lot of integrity. His grow lights last for the tens of thousands of hours he promises, with little if any decline in light intensity and spectral output. We’ve never had even one of his lights fail for any reason!

Some of his models have magnifiers on the LED chips for increased intensity and penetration in high ceiling grow ops, and he also has lights for regular grow rooms and even SCROG low-height growing.

We’ve found that although Lush LED grow lights produce slightly less harvest weight in competition with HID (including double-ended bulbs), they produce 10-15% more cannabinoids and terpenoids, and you save several days off of each season because your cannabis plants grow and mature faster. So when you calculate the total long-term cost of buying his LED light and running it versus running HID lights and replacing bulbs every season or two, Lush grow lights are a far better investment than HID grow lights.

As regards leaf bleaching and the evils associated with it, Matt sent us convenient three-dimensionalized charts that show exactly how many photons are reaching plants at various grow light heights above the canopy. We’ve used his lights that replace 1000-watt HID at close as 18-22 inches from the canopy with no burning, bleaching or heat stress. No other LED brand or model we’ve tested provided the close distance-to-canopy, canopy penetration, and successful harvest outcomes that Lush grow lights provide.

Dominator 2xXL high intensity Lush Lighting LED Agriculture  Grow Light.jpeg

Another reason we’re praising Lush is that Matt and his crew are friendly, honest, transparent, and savvy when growers ask what lights to buy, how to use Lush LED grow lights, or need light repair.

Yes, they’re super busy because their lights are in high demand and because they’re a small all-American company, but they definitely know marijuana growing and LEDs, and are passionately dedicated to your grow op success.

One final note—you can’t trust those so-called “LED review sites” that are so pervasive online. Notice these sites say little or nothing about harvest weight, cannabinoid and terpenoid percentages, strains grown, what they competed the test LED model against, and other relevant details.

They don’t show marijuana grow op photos of their alleged LED grow light test, and I don’t think these reviewers are actually using the lights to grow marijuana, if they used them at all!

Frankly, most of those so-called reviews are more like paid advertisements than an honest marijuana grow room evaluation of how the reviewed light actually works for cannabis growers. I also notice those review sites are often in business with the LED manufacturers, even to the extent of blatantly trying to sell the reviewed grow light at the end of the article. I don’t trust any of them!

LED Grow Lights: Ask Before You Buy

Premium LED grow lights that can replace 600/1000-watt HID grow lights cost at least $1400 if not much more. Before you buy an LED grow light, do your due diligence and make sure you know exactly how the light will work for you, and every little thing you need to know about distance from canopy, heat, warranty, repairs, and other details.

Sometimes I still use one or two HID grow lights along with LED, but only during the coldest winter months. Unless I’m doing grow light testing of other LED brands, I use only the Lush LED, and get great results. Other growers in our magazine consortium do the same.

If you’re looking to get your first LED grow light, already have one and are having problems, or want more LED lights, contact the manufacturer immediately. Anonymously explain to them the height, air conditioning, strains and other configuration basics of your indoor grow op, and ask these questions:

  • How far from the plants does the light have to be for seedlings/clones, grow phase, and bloom phase?
  • What is a conservative estimate of the actual square feet of grow space that can be adequately lit by the lights you’re considering?
  • What spectrum does the light put out and why was that spectrum chosen?
  • How much actual electricity consumption does the light require?
  • Does the light contain Osram or Cree chips, which are the industry standard, rather than inferior chips?
  • Was the light spectrum tuned specifically for cannabis plants?
  • Can this light be used from start to finish?
  • What warranty, customer support and other assurance policies are in place?
  • How long has the manufacturer been in business?

Be sure to look at online reviews of the manufacturer and lights, but not from online review sites. Instead, look on grower forums, Google reviews, Amazon reviews and other places where reviews are more likely to be authentic rather than just coming from paid shills.

And pay attention to how friendly, honest, and helpful manufacturers are when you ask for information. If you email or call an LED manufacturer and it takes them forever to get back to you, or they don’t provide comprehensive, useful information, take that as a sign that you don’t want to do business with them.

Problems with manufactured LED grow lights have led some growers to start making their own. According to my grower friends who’ve made LEDs, it’s not all that hard to do, saves you tons of money, and gives you the opportunity to customize your lights to exactly match your grow space and growing style. Several LED-maker websites and forums can be found online, including this LED self-manufacture forum.

In summary, the best LED grow lights use far less electricity and generate much less heat than HID, and last far longer than HID units. Used correctly, they can provide yields nearly equal to HID, but at a much lower cost.

If you find or can build an LED grow light make and model that works well for your grow room, it will be much better for your plants and profits than using HID. Now that you’ve read this article, you’re set up to know what questions to ask and what you’re getting into when you buy an LED grow light.

When you look at that dense, frosty bud grown under our Lush LED grow lights (shown in the main photo for the article), you see what LED lights can do if they’re the right lights! Overall, I’d say that LED grow lights are the wave of the future. If quality manufacturers like Lush keep on pushing innovations, efficiency, spectral specificity and garden success, HID grow lights could be a thing of the past within ten years.