The Basics: What are the Best Grow Lights for Hydroponics?

What are the best grow lights for your hydroponics setup? In the hydroponic grow room, there are several competing methodologies when it comes to grow lights. One group of hydroponic cultivators sits firmly in the HID lighting camp, while others are firmly in the LED camp.

Eventually, as you go deeper into your indoor operation, you’ll need to know the science behind grow lights. But today, you need to get the fundamentals. 

What indoor grow light is best for beginners, has the best energy efficiency, and ultimately, will produce the biggest yield? If you are growing hydroponically, here are the basics of indoor grow lights. 

What is HID Lighting?

Conventional lighting used in indoor cultivation is high-intensity discharge technology or HID. This technology sends an electrical arc through a glass bulb filled with different chemical vapors. Different chemicals produce different light ‘colors’ or light spectrums.

There are two standard options for HID indoor grow lights: Metal halide (MH) and High-Pressure Sodium (HPS). 

Both types have dominated the hydroponics industry because of their sheer intensity (lumen output). In addition, they have been the most affordable lighting (at least in terms of upfront investment).

The downside to HID lights is their energy efficiency. Although today’s models are much better than their older counterparts, they are energy hogs compared to newer technology like LED lighting.

Even if they are cheaper in the initial investment, you’ll end up paying for more electricity in the long run.

Both MH and HPS options burn hot, which requires additional investment into a powerful ventilation system. The heat also means these fixtures burn quickly, which means higher replacement costs. 

Metal Halide (MH)

Metal halide fixtures contain mercury and metal halide vapors, which light up with an electrical arc. The typical lifespan for a MH fixture is 15,000 hours.

The gas type produces an intense white light, which falls on the blue to yellow end of the visible light spectrum. This is perfect for plants in veg or any vegetable grown for its leaves (rather than its flowers).

Cannabis cultivators often rely on MH grow lights to pump out bushy leafy growth before switching to HPS for flower.

High-Pressure Sodium (HPS)

The other type of HID lighting used for growing indoors is HPS. These operate under the same principle as MH, sending an electrical arc through a gas, but this time it’s a sodium gas. The lifespan of an HPS fixture is roughly 25,000 hours.

HPS lamps tend to emit a warmer light than their MH cousins. This means they make for an excellent grow light option for flowering plants. As a result, many cannabis growers switch over to an HPS room during flower.

What is LED Lighting?

LED stands for light-emitting diode. Technically, LED lights are composed of groups of tiny semiconductors that glow when tied into an electrical current. 

A typical LED grow light contains hundreds, if not thousands, of individual diodes, which together emit enough light to feed your plants.

Although LED lighting got a bad rap when it first entered the market, the technology has come a long way over the last few decades. 

This means LED grow lights produce an equivalent light spectrum and intensity to HID options but with considerable energy savings.

Many factors play into energy efficiency (fixture, location, consumption), but most resources suggest LEDs save at least 50 from a standard HPS fixture.

Plus, the LED lifespan is substantially longer than any HPS fixture. Most quality LED lights will run for at least 70,000 hours, with minimal light degradation. 

What is the Best Grow Light for Beginners?

If you are just starting out, you’ll want to keep it simple and affordable. Most newbie growers focus on one standard grow tent with a single grow light. You’ll want to purchase something that covers both veg and flower, and one that doesn’t need much in the way of ventilation.

The best grow light for beginners is an LED grow light. Options like KIND Led or the Horticulture Lighting Group offer single fixtures that work for a 4’x 4′ grow tent, and produce a spectrum ideally suited to both veg (blue waves) and flower (red waves). 

Although all LEDs produce some heat, both these brands use reliable passive-cooled design features. This means you won’t stress so much about the temperature creep in your nutrient solution. 

What is the Best Grow Light for Energy Efficiency?

Hands down, the best light for energy efficiency is an LED grow light. 

How do we know this? Calculating the efficiency of any light fixture boils down to looking at the lumens produced per watt consumed. 

In one study comparing the efficiency of MH vs. HPS vs. LED (among others), researchers Elena Dănilă and Dorin D. Lucache tested different lights for growing tomatoes. 

When they crunched the numbers, they determined LEDs were 51 percent more cost-effective than other technologies. The energy costs in this controlled study were as follows:

• LED: $244.8
• Metal Halide: $2016.00
• High-Pressure Sodium: $2016.00

Considering hydroponic systems do pull more energy (under most circumstances) than a soil-based system, any energy savings you can reap from an efficient light fixture will pay off at the end of the day.

What is the Best Grow Light for Yield?

Out of all the questions here, this is the most difficult. There are so many factors at play, from genetics to pruning techniques to cultivator experience. 

Anecdotally, you’ll hear some growers tote the benefits of each. Still, LED is slowly taking over as the technology gets better and becomes more affordable.  

In a video comparing the two systems, one cultivator reported better results with two sour gelato strains grown under HPS and LED. His LED flower is “Much bigger, much frostier, and they are like rocks. They are rock hard.” 

At the time of writing, few controlled studies had looked at HID vs. LED cannabis yields. A few are looking at other crops, though, including a hydroponic lettuce operation. 

As per one study, “LED light treatments showed improved homogeneity of plant mass across the entire area while HPS light treatment showed potential for slightly higher production in limited areas.” 

However, “While there is an intensity difference between both light treatments, mass plant production remained similar. “

The Best Lights For Hydroponic Grow Rooms: LED Grow Lights

For anyone just getting into hydroponic growing, LED grow lights are increasingly worth the investment. Better energy efficiency, better yields, and they produce much less heat than the conventional options.

Although HPS and MH fixtures continue to produce high-quality crops, LED grow light technology is giving these traditional options a run for their money. 

Do you grow hydroponically? What fixtures do you swear by?