The Complete Guide to Lights for Indoor Cannabis Growing from HID to LED

Whether you’re growing indoors or in a greenhouse, lighting equipment selection is one of the most important decisions a cannabis producer can make. For decades, high-intensity discharge (HID) lights were the name of the game. But today, LED lights are transforming the way cultivation spaces are structured—literally—by making vertical grows and more efficient use of space a real option for the first time. 

What are HID lights?

Not to be confused with incandescent or fluorescent lights, HID lights work by creating an electrical arc between two electrodes in a bulb filled with an ionized noble gas. They’re popular for all sorts of applications that require a steady stream of bright light spread over a broad area. For example, HID has become a popular choice for stadium and gymnasium lighting, streetlights, film and theatrical lighting and, of course, agricultural grow lights.

What are LED lights?

LED lights—short for “light-emitting diode”—were invented over a century ago, and NASA has been experimenting with their use as grow lights since the 1980s. But advances in LED technology have only recently made possible widespread commercial use of the lights in agricultural and hydroponic settings. 

Now that you know the technical differences between these two types of lights, the next step is to identify which is the best fit for your facility. Knowing the pros and cons of each lighting category is the first step to making an informed choice for your grow.

Cost of HID Lights vs. LED Lights

HIDs have been popular with cultivators for years because they are cheap, sturdy and provide light in a concentration and spectrum compatible with the needs of cannabis plants. They’ve been the near-ubiquitous industry standard for both indoor and greenhouse grows because of their affordability and utility.

LED lights are more expensive than HID up front, but less costly to operate over time when you take into consideration other contributing factors like rebates, energy savings, lamp replacement and ongoing maintenance. From a cost standpoint, the benefits of LED can beat out HID relatively quickly when you take the reduced air conditioning requirements into account.

That’s because one of the most significant differences between HID and LED lights is how much heat they produce. HID lights run notoriously hot, which limits how close they can be situated to plants as well as the HVAC tonnage an operator will need to compensate. By choosing LED lights, growers can also reduce the operating costs of the air conditioning and dehumidification systems. 

Cannabis Yields from HID Lights vs. LED Lights

A skilled grower can achieve a strain’s maximum yield potential with quality HIDs—indeed, cannabis cultivators have been doing so for years. The same is true of a grow that utilizes quality LEDs. It’s not as if one lighting option is better for yields specifically, but LED lights do offer certain advantages for growers who want to maximize the amount of flower per square foot grown.

Because LED lights don’t produce as much heat as incandescent or HID lights, their widespread availability has caused something of a revolution in cultivation facility design. Suddenly, growers aren’t limited to placing their lights at least 4-6 feet away from the tender leaves of cannabis plants. With LED lights, growers can implement stacked systems to make the most efficient use of both vertical and horizontal cultivation space, as well as finesse the inputs needed to maximize any given strain’s yield potential.

Power Consumption from HID Lights vs. LED Lights

There’s no getting around the fact that HIDs, effective and affordable as they may be, are power hogs. HIDs use more energy than LEDs to produce the same amount of light. Growers are now achieving with a 630-watt LED fixture what they used to achieve with a 1,000-watt HID fixture. 

For example, an HID and an LED light each rated 630 watts will actually produce the same amount of heat because they use the same amount of energy, or watts. However, their PAR and lumen output might be quite different. The LED fixture will produce a greater amount of light with the same amount of energy, and because it runs at a lower temperature that LED fixture can bring PAR right to the leaves, wasting less light. 

As long as that light is within PAR targets, the cannabis plants lit with LEDs will get more of what they need while consuming less electricity. Increasingly, growers are adjusting the amount of light delivered to cannabis plants at different phases of development, as well as the spectrum of that light within PAR, as part of cultivation automation and crop steering techniques. 

Not only do operators experience electrical savings on a watts-per-square-foot basis, but because LEDs are more efficient and give off less heat over that same square footage, the resulting HVAC tonnage requirement is also reduced, lowering a facility’s monthly electrical expenditure even further. In a large facility, these savings can be massive.

Maintenance and Operating Expenses from Cannabis Lighting Equipment

That’s not the only advantage that LEDs offer in terms of reduced maintenance and operating expenses. LEDs last a lot longer than HIDs do. A quality LED can last up to 10 years before it needs to be replaced.

HIDs, on the other hand, fall short in this respect. Anyone who’s ever run several hundred HIDs can testify to the amount of time, money and safety risks that go into keeping all the lights on. Between keeping up with the repair and replacement of bad lamps and bad ballasts, and the constant churn of burnt-out bulbs, operating a lot of HID fixtures can be a big chore. 

Replacing heavy ballasts or leaning over a swath of mature, flowering plants 12 feet in the air to perform maintenance is not only inconvenient and time-consuming, it increases the risk of accidents for cultivation staff. Every time a room’s worth of HID lights need to be replaced, someone is getting up and down a tall ladder all day, while handling glass and harmful gas. It’s stressful for workers and a liability for operators—hardly a compelling scenario.

How long an HID lamp can achieve peak yields and quality before it must be replaced is a frequent point of debate for cultivators. But the general consensus among top producers seems to be that lamps should be replaced every 6 months. Some go longer, some shorter. The average double-ended HID lamp costs anywhere from $60 to $100+. At 2 lamps per fixture, per year, it doesn’t take many years (maybe 2) for the lamp costs alone to justify going LED.

Environmental Sustainability of HID Lights vs. LED Lights

LED lights have become extremely popular in residential, commercial and agricultural settings for the sustainability of their long lifespan and reduced energy consumption. The cannabis industry, like many burgeoning sectors, has yet to fully prioritize sustainability over growth. LED lights are simply one of the most efficient, environmentally friendly options available to commercial growers, whether you choose them for the cost savings or the sustainability cred.

HIDs, on the other hand, represent the significant waste that still plagues much of the cannabis industry. Spent lamps—which, remember, have a lifespan of roughly 6 months—frequently end up in landfills, where their toxic mercury content can leach into the groundwater. While lamp recycling programs exist in many municipalities, not all operators take advantage. And it’s yet another time-consuming, sometimes dangerous task for cultivation staff to box up and transport spent lamps to such facilities without breaking any of the glass or coming into contact with the contents.

Should I Choose HID or LED For My Commercial Cannabis Grow

If you’re starting your cannabis cultivation construction from scratch, there’s every reason to choose LED for all of the above reasons. It’s quickly becoming the go-to option for cultivators. But even for those producers retrofitting or upgrading an existing cultivation facility, many states and municipalities offer an increasing number of rebates that take the sting out of the upfront costs associated with changing up your lighting system and other foundational equipment for your grow. 

Finally, for sustainability reasons, state governments and other stakeholders now routinely offer financial incentives for grow renovations that incorporate not only LED lights, but also smaller HVAC systems, dehumidification and condensation recapture, wastewater reclamation and automation systems. As we like to say, every facility, grower, and situation is different. From facility and equipment limitations to budgets, goals and desired outcomes. If you are curious about what the best lighting application is for your project, give us a shout and we would be happy to discuss your project.