You would assume at this point in time, indoor growers would have long ago settled the debate over the best grow light. Surely, by now, either an LED or an HPS lighting system would have been declared the winner in terms of efficiency, intensity, profitability, and effectiveness for growing plants with artificial lights.
Today, the debate rages on between cultivators. In all fairness to the growers, it’s not as if either lighting system is a clear winner. Each system has pros and cons, neither ticks all the boxes.
Depending on your grow room setup, budget, expectations, and personal preference you could easily swing either way.
It takes an engineering degree to wade through the many online resources and technicalities defining an HPS vs. LED. As soon as you’ve come to a conclusion, another article will refute everything you’ve come to believe. The best lighting for an indoor grow room is still a frequent, and colorful, topic of conversation between growers.
Are LED grow lights worth it? Does 'the best' cheap LED grow light even exist? At the end of the day, it comes down to your situation. Depending on grow room specifics, budget, and crop intention, you could come to some very different conclusions about which system is going to work best.
In an attempt to shed some light on both sides of the debate (no pun intended of course), this is your go-to resource for the basics behind LED and HPS lights.
(Want more information beyond just a comparison? Check out our expansive grow light resource)
What Are HPS Lights?
HPS, or high-pressure sodium, light bulbs are the conventional grow lights long used in indoor cultivation. They are a high-intensity discharge light (HID) bulbs. You may also hear about metal halide (MH) light bulbs, which is the other type of HID. Both models use a sealed chamber, filled with different gases. The bulbs have two electrodes, which ignite the gas when turned on.
Depending on the style of the bulb, each containing a different type of gas, the bulb will emit a different spectrum of light. The HPS bulb usually leans towards the orange, red side of the spectrum, and the MH style leans towards purples, blue undertones. Cultivators often rely on a unique combination of the bulbs to hit precisely the range your plants need, when they need it.
HPS lights have maintained their popularity, even in the face of new lighting systems because of the sheer intensity and strength of the light they produce. This intense light comes with a similarly fierce emission of heat. This heat usually requires more investment in a proper HVAC and ventilation system.
What Are LEDs?
Light Emitting Diodes, more commonly known as LEDs, are a relatively new invention. They are slowly but surely changing the way indoor grow operations accomplish lighting. Instead of an ignition type lightbulb, power travels to a microchip, which then passes through a small diode. The light spectrum produced by an LED is highly customizable, and can at least in theory, provide the full spectrum required for any plant.
They are also highly directional. HID lights, which are long cylindrical tubes, emit light in all directions. That's 360 degrees of light, shining out in all directions, but indoor cultivation will only need roughly 90 to 180 degrees of light, shining downwards on the crop. Vertical farming setups will take advantage of a more substantial portion of this light, but still, much of the list goes to waste. LED systems, on the other hand, are easily manipulated direction wise, reducing the wasted energy seen in conventional HID systems.
LEDs are a relatively new and evolving technology. As such they are typically at least 50 percent more expensive to purchase and install than their HID counterparts. Depending of course on quality. The best cheap led grow lights are still more expensive than a similar HPS version. However, over the lifespan of the LED lighting system, cultivators see returns on the initial investment. Some estimates place the energy savings from LED lights between 35 to 70 percent over more conventional systems
Other bonus points for the LED industry is the exponentially longer lifespan. HPS lights typically burn out between 6,000 to 24,000 hours, while an LED may last upwards of 200,000 hours. They also are damage resistant, require little to no-system upkeep, and do not degrade as quickly as HID systems.
LED Grow Lights vs. HPS
But even if you know the differences between the two styles of grow room light options, do you know what kind of light is best for growing plants with artificial lights? As with any technology, there are pros and cons to each system. To get a better idea of the costs and benefits of LED vs. HPS, let's break down into an easy to digest list of the individual pros and cons.
HPS Pros
- Relatively affordable initial investment.
- High-intensity light output.
- HPS systems are by this point standardized across the industry; it is easy to make side-by-side comparisons.
- HPS quality consistency, a cheap system is still moderately useful.
HPS Cons
- Intense heat emissions require advanced ventilation systems.
- At least 50 percent of the light and energy goes to waste.
- The light spectrum, while Intense, is not tailored to the needs of the crop. Most growers use two systems (MH and HPS) to produce the spectrum needed during the life cycle of the plant.
- Comparatively short lifespan.
- Requires high level of repair, management, and monitoring.
LED Pros
- Upwards of 70 percent energy savings.
- Exponentially longer lifespan compared to HPS.
- Full-color spectrum, customizable to the crops needs.
- Less energy waste, light emissions only 180 degrees instead of 360 degrees.
- Zero to no heat emissions, which means closer placement to the crop and less need for expensive HVAC systems.
LED Cons
- Usually at least 50 percent more expensive in upfront costs.
- Little standardization across the industry, which makes it difficult to compare different makes and models.
- Produce little if any heat, which while also a benefit, can be challenging for greenhouse growers or those in colder climates.
- Although improving, many models produce lower intensity light than an HPS model.
Are LED Lights Good for Plants?
A long time ago, LEDs were efficient, but not super practical for growing indoor crops. Their intensity couldn’t compete with the levels coming out of HID models. Today, engineers have made massive improvements to the technology, and are using the available light spectrum of an LED to their advantage.
LEDs developed for indoor cultivation are designed to produce the ideal color spectrum required by the crop. Typically, for cannabis growers, this means some combination of white light and a frequency lovingly referred to as ‘blurple’. Blues, purples, reds all combine to stimulate a productive crop.
With the capability to hone in the light spectrum to suit the needs of your plants, LED lights can be very effective for final harvest. During the vegetative stage, blues and purples boost strength and bushiness. Turning the dial towards reds and warmer tons during the flowering stage promotes flower growth. Certain other frequencies in small doses, like ultraviolet, maybe even green, can boost cannabinoid and terpene profiles.
LED lights are not ‘bad’ for your indoor harvest, but their benefits are much more powerful when the cultivator knows what they are doing. Knowing when and how to adjust the light spectrum, and schedule makes a huge difference when using LED lights. They are not a ‘set it and forget it system.’
Best LED Grow Light for the Money?
Let the debate begin!
There are more than enough opinions online about the best LED grow light for the money, but if we were to place bets, we’d put our money on the ROI-E680s by Growers Choice priced at $749. The ROI-E680 was new to the market as of May 2019 but was upgraded in 2022 and performs similarly to the Gavita 1650e which has a similar PPF output and costs a lot more.
The ROI-E680s boasts a powerful 1700 umol/s PPF output and draws only 680w from the wall. To put that into perspective; a 1000w DE (double-ended) fixture that is commonly used in warehouse grow operations puts out about 1850 umol/s.
That's a powerful punch for a 680w light!
How to Build a LED Grow Light System
If you are just getting started with your grow room set up, and don’t have a technical bone in your body, a DIY LED grow light system might not be the best route. Building a custom LED grow light system without any technical know-how will waste your time, money, and could even lead to crop failure.
Until you get a handle on growing plants with artificial lights, you’ll want to stick with high quality LED brands, such as Electric Sky or Growers Choice. With all the other influences over crop yields, you’ll want all the help you can get from professionally designed lighting systems.
With that said, maybe you do have a bit of skill when it comes to breaking things apart and putting them back together. If you do, it can save you quite a bit of money (although maybe not time), to design your own LED system.
There are many resources from established tech-growers available online. One of our favorites includes growmau5 and his professional, insightful, and detailed series on youtube. There are of course many other indoor growing guru’s who can walk you through their set up as well.
If a DIY system is what you are after, here are a few tips to get started:
- Know your grow room: dimensions, capabilities, power, ventilation and more.
- Know your crop: Every species and strain will need subtly different light requirements.
- Invest in Quality Brands: cheap LeD lights from China, while appealing and affordable, often make inaccurate claims about input and output.
- Purchase the Right Tools: Invest in a light meter (to measure lumens), and a light spectrum reader (to measure light spectrum). It can also be of benefit to have a power monitor, to get an accurate reading on how much power your system is pulling.
Can You Use Regular LED Lights for Grow Lights?
Cheap LED lights have flooded the market, and many home growers have purchased them hoping to take advantage of their efficiency. However, cheap led grow lights while appealing in price will typically lead to unappealing final yields, and maybe even higher electricity bills than you had hoped.
Cheap low-quality brand, sourced overseas, often make false or misleading claims about their energy use and their output. A good rule of thumb is to look for chips with 3w, or 5w for the most efficiency. If you do have issues with the product, consider the reputation of the company’s customer service team.
You’ll also want to look for grow lights, which are specifically designed, or at least customizable, to your crop of choice. A white light spectrum, which is standard with regular LED lights, will not meet the requirements of high-output cannabis grow operations. Blues, reds, and ultraviolets are crucial to high returns.
Finally, you’ll want a high-output LED source. Standard non-grow light LEDs are not designed for high-intensity output. The light won’t penetrate the canopy, and won’t produce the light needed to a prosperous crop.
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We never said the decision between HPS and LEDs grow lights was going to be an easy one. While LEDs have come a long way over the last decade, the best cheap LED system is still very likely going to be out-produced by a cheap HPS system.
The real improvements come with a large upfront investment. A high-quality LED system, like the ROI-E680 by Growers Choice, may sting a little after the initial investment, but the lifespan and energy savings work out over the long term. The final decision on growing plants with artificial lights comes down to your own research, budgetary restrictions, and personal preference.