LED grow lights vs HPS for cannabis

Many have already upgraded their grow light from HPS (High Pressure Sodium) to LED. For those that haven’t yet splashed the cash on an LED, the big question is whether the cost will be worth it. If you’re growing in a typical 1.2m x 1.2m (4ft x 4ft) tent most HPS growers will probably be using a 600W HPS. Budget 600W fixtures start from as little as €/£/$50 including reflector and ballast. A 400-500W LED required for a similar grow space might cost up to ten times that.

So is the extra cost of LED really worth it?

Growing cannabis with LED vs HPS grow lights

Auto Cinderella Jack grown indoors with LST and 240w LED

Although some growers use CMH (ceramic metal halide) lights, the majority of growers tend to use either LED or HPS. HPS can’t be beaten on price, but it can when it comes to the quality of the buds grown. LED costs have reduced dramatically in recent years but a 400-500W fixture suited to a 1.2m x 1.2m (4ft x 4ft) tent would still cost around/up to €/£/$500.For many home growers an LED grow light is one of the most expensive grow room upgrades they will make.

What are LED grow lights?

Auto Blackberry Kush grown indoors with LED grow lights

Using numerous small LED ‘chips’ an LED grow light has an optimised spectral output to ensure healthy cannabis growing. Typically, they have a warm white light output with peaks in red and blue to ensure healthy cannabis veg growth as well as a productive cannabis bloom stage.

LED grow lights tend to produce less waste heat energy than HPS, making LED the preferred choice for those that struggle with high grow room temperatures.

Despite their relatively high cost, LED grow lights have never been more affordable. As LED tech continues to evolve, efficiencies keep increasing. These days all serious growers tend to opt for LED. Dutch Passion see cannabinoid levels and terpene levels increase when LED is used instead of HPS.

What are HPS grow lights?

HPS lights are the lowest cost option and many growers use them with great success. High voltages excite atoms of Sodium causing light to be produced. HPS does emit inherently higher levels of IR heat than LED grow lights.

But to some growers, growing in winter for instance, the extra radiant heat from an HPS may actually be useful. Conversely, with increasingly hot summers, HPS lights can make summer-growing difficult.

But when used well, HPS lights can produce great quality buds whether autoflower seeds or feminised seeds are grown. However, most professionals would argue that the very finest quality buds tend to be grown under LED.

LED vs HPS cost-efficiency

In the early years of LED many hoped that a 600W HPS could be replaced with perhaps 150-200W of LED. Those dreams never happened, and many LED suppliers would recommend 400-500W of LED for a typical 1.2m x 1.2m grow area. So, a LED for a given grow area typically uses less wattage than HPS, but not by a massive margin.

PROS

LED grow lights

For the same PPFD (light) levels you can generally use less Watts with LED vs HPS. Electricity costs will often be 10-20% lower.
LED wavelengths are selected specifically for cannabis cultivation, optimising quality.
LED tends to produce the highest THC levels and highest terpene content.
LED wastes very little energy on heat production.
LEDs are continuously improving tech with steadily improving efficiencies year-on-year.
Substantial R&D investments are routinely improving LED performance, efficiency and power. LED continues to get better and better.

HPS grow lights

HPS is the established cost leader.
Good results possible for budget prices.
Waste HPS heat energy can be useful to maintain grow room temperatures in winter grows, but in general waste heat from HPS is regarded as a nuisance.

CONS

LED grow lights

LED is an expensive upgrade.
Some growers take a couple of grows to adjust to growing with their new LED.

HPS grow lights

HPS is the established cost leader.
Good results possible for budget prices.
Waste HPS heat energy can be useful to maintain grow room temperatures in winter grows, but in general waste heat from HPS is regarded as a nuisance.

LED vs HPS ease of use and safety

A well-built HPS grow light is perfectly safe and easy to use. So is a good LED grow light.

PROS

LED grow lights

LED lights should last many years, over a decade+ for most hobby growers.
LED allows the used the option to fine-control power settings.
LEDs generally run at inherently lower temperatures than HPS. Some growers feel that a modern, well-built LED is inherently safer than older HPS lights with their hot-running ballasts.

HPS grow lights

HPS lights are available everywhere and easy to use. Most serious growers tend to avoid the budget models and select a solid, well-built brand.

CONS

LED grow lights

New LED tech ages quickly. The best LED grow lights from 3-4 years ago look expensive (and perhaps slightly under-powered) by current standards. Today’s best LED lights will also be superseded as technology advances. But that shouldn’t stop you upgrading to LED. Optimising your grow room conditions is the sign of a serious grower keen to reach new quality levels.

HPS grow lights

HPS light will need regular bulb changes. Most serious growers change the HPS bulb after 2-3 grow cycles.
Fine power adjustment is not possible with HPS, though some systems allow basic power controls.
HPS lights produce much more heat than an LED. This can cause plant stress and reduce final bud quality.

LED vs HPS yield

The Ultimate femseeds scrogging start of flowering led grow lights top and bottom buds flowers

Both HPS and LED grow lights will produce healthy yields. But the LED grower enjoys a fundamental advantage and will generally achieve measurably higher THC & terpene levels than would be possible with the same genetics in an HPS grow.

In one experiment, Dutch Passion saw identical genetics deliver 17% THC under HPS and 23% THC under LED. That’s a significant increase that transforms average buds into memorable buds.

However, few LED growers would claim significantly superior yields compared to HPS. The benefits are in the quality/potency. That said, LED grow lights generally use 10-25% less power (Watts) compared to a comparably bright HPS light. A grower with a 1.5m x 1.5m (5ft x 5ft) grow room might use around 750W of LED whereas an HPS grower might use a 1000W HPS in the same area, with broadly similar yield expectations. The LED grower has the advantage of superior THC levels, slightly lower electricity consumption and a lower need for air-conditioning/cooling compared to the HPS grower.

PROS

LED grow lights

For beginners, LED will often produce similar yields to HPS whilst using a little less energy and producing less heat.
Expert growers can pump up the yield with the latest generation LED lights to the next level. Thanks to the high efficiency and maxed out PPFD levels, experts can get between 2-3 gram per watt.

HPS grow lights

HPS lights deliver good yields.
Some HPS growers find the humidity levels are lower and easier to manage due to the higher temperatures found with HPS. High yields and compact buds are often achieved by skilled HPS growers growing good quality cannabis seeds.

CONS

LED grow lights

It can take a few grows for beginners making the switch from HPS to LED to get used to LED growing e.g. watering frequency etc.

HPS grow lights

If the grow room gets a little too warm the HPS-grown buds may become a little fluffy with a less-desirable structure. HPS lights do produce more heat than many growers would prefer.

LED vs HPS bud quality

Bud quality, which for many means high cannabinoid levels in combination with richer terpene levels, is probably the biggest benefit cited by those that have upgraded from HPS to LED. And of those that have switched to LED, few would want to go back to HPS.

The inherently superior quality levels arise thanks to the better light spectrum from the best LED grow lights. This means higher THC levels as well as other minor cannabinoids. Heat stress is reduced when switching from HPS to LED, another factor that moves quality in the right direction.

It’s worth adding that growers chasing the very highest THC levels and dankest terpene loading also use supplementary UVA/UVB lights. Not only do these tend to maximise cannabinoids/terpenes, but they may also help reduce airborne pest activity too.

Of course, buying the best cannabis seeds is essential. Dutch Passion have conveniently grouped all of their highest THC cannabis seeds together in one collection, making it easier to select from the most potent strains.

PROS

LED grow lights

Highest bud quality with maximised cannabinoid levels.
Highest terpene loading, expect (dependent on the genetics) >1% terpenes in the cured buds.

HPS grow lights

Good bud quality
Good terpene levels
Lights are cheap

CONS

LED grow lights

LED is expensive to purchase.

HPS grow lights

HPS can produce good quality levels, but they can’t match LED results.

Why are LED grow lights better than HPS for cannabis?

There are a variety of reasons why LED is regarded as superior. Different growers place different weightings on the LED benefits.

A bar-style LED produces very even, consistent light levels across the canopy from corner to corner, maximising the use/output of your grow space.

LED output is very consistent, declining just a few percentage points even after thousands of hours of use. In typical hobby-grower conditions a good grow light might be expected to give a decade or more of faithful service with no replacement bulb costs. HPS lights require bulb changes every few grow cycles.

The LED light spectrum chosen by leading manufacturers produces truly excellent results with crystal covered buds.

LED will generally run cooler than HPS, reducing heat stress, improving harvest quality and reducing the need for air-conditioning.

A LED grow light will typically consume less energy to run – meaning lower electricity bills vs HPS.

Whether you’re growing feminised cannabis seeds and/or autoflower seeds, LED will maximise the potency of the buds.

LED vs HPS grow lights FAQ

Autoflower cannabis plant light schedule

Bud quality, which for many means high cannabinoid levels in combination with richer terpene levels, is probably the biggest benefit cited by those that have upgraded from HPS to LED. And of those that have switched to LED, few would want to go back to HPS.

The inherently superior quality levels arise thanks to the better light spectrum from the best LED grow lights. This means higher THC levels as well as other minor cannabinoids. Heat stress is reduced when switching from HPS to LED, another factor that moves quality in the right direction.

It’s worth adding that growers chasing the very highest THC levels and dankest terpene loading also use supplementary UVA/UVB lights. Not only do these tend to maximise cannabinoids/terpenes, but they may also help reduce airborne pest activity too.

Of course, buying the best cannabis seeds is essential. Dutch Passion have conveniently grouped all of their highest THC cannabis seeds together in one collection, making it easier to select from the most potent strains.

There are a variety of reasons why LED is regarded as superior. Different growers place different weightings on the LED benefits.

Yes. The cannabis plant doesn’t know where the light energy is coming from or how it is being generated. Some growers deliberately introduce an HPS light into their LED grow room to help maintain winter grow temperatures.

Yes. The astute grower will have an idea of the light output from his LED /HPS lights and try to match light intensities at canopy levels when switching. This makes the transition easier from the plant perspective with less stress/shock.

Do your homework and spend time reviewing the different brands. The YouTube channel from Migro offers unbiased testing. They also make some great value lights of their own.

We really recommend some wrap-around sunglasses for use in your tent. Many older growers wish they had protected their eyes at a younger age. Modern LEDs really are blindingly powerful. Connoisseur growers may prefer to buy some colour-corrected sunglasses to give the ‘best’ views of their plants, but many simply use off-the-shelf sunglasses with a neutral tint.

The websites from the leading LED grow light companies have useful charts showing the recommended lights for a particular sized grow area. They also offer useful advice on recommended hanging heights and power intensities at various stages of plant growth (cannabis seedling stage, vegetative stage, bloom stage).

LED grow lights have benefitted from increasingly competitive prices and technology that gets slightly cheaper and more gradually more powerful each year.

The following table provides a very rough guide to the power levels of comparable HPS lights and their LED approximate equivalent. However, the guide is only approximate since different LED grow lights use LED ‘chips’ of varying efficiencies.

HPS	LED
400W	250-325W
600W	350-500W
1000W	600-800W

LED vs HPS for cannabis growing summary

If you haven’t already taken the financial plunge, there has never been a better time to invest in an LED upgrade for your grow room. Sure, just like computer tech, LED grow lights continue to get more powerful and more affordable. But that shouldn’t deter you from investing now if that’s the upgrade that your grow room needs. All cannabis grower pride themselves on their crop quality. And if you’re still growing under HPS grow lights then you will be very pleasantly surprised by the step-up in quality levels from an LED powered grow room.