Growing Cannabis With Lec Lights: Pros and Cons

Brand new technology can be a cautious buy, especially if the results are unproven. Thankfully, as the use of LEC lights spreads, reports of their efficiency and ability to improve yields are enticing an increasing number of growers.

It seems that with each passing day, a new technology or piece of equipment arrives on the cannabis scene promising better yields or reduced cost. Like all things in life, those kind of statements are easy to say, but hard to back up. If, however, cost-effective growing environments sound like an appealing topic, LEC grow lights could be the next step in future-fit lighting solutions.

With increased lumens per watt, the promise of improved yields, and a more natural light spectrum, the statistics behind LEC—or as they are otherwise known, CMH lights—certainly seem to stack up. Is it worth considering though? And what limitations does the current lighting market have that makes an upgrade worthwhile?


Presently, if you opt to grow indoors, sufficient lighting is essential to stimulate the process of photosynthesis. Typical options can be split into four major categories: fluorescent grow lights (CFLs), metal halide (MH), high-pressure sodium (HPS), and light-emitting diode (LED).

Firstly, CFLs are the most common among novice growers only focussing on a few plants. They are widely available at hardware shops, produce an average amount of light, and are technically capable of taking your seedling all the way through to harvest as long as the rest of your growing environment is in optimal condition. Given they are a standard household item, the lifespan of these bulbs is sporadic, but overall they provide middle-of-the-road performance. CFLs are not usually recommended for the flowering phase if you can afford better, since they are simply too weak to produce a bumper harvest.

MH and HPS lights form the cornerstone of setups for hobby growers all the way up to full-scale commercial operations. The former is favoured during the vegetative stage while the latter is preferred during flowering. Despite their different uses, they both have something in common: incredibly high running costs. And while both lights are responsible for impressive yields, as the industry moves towards a more efficient and environmentally friendly approach, MH and HPS lights appear very old-fashioned.

Considered the new kid on the block, LEDs offer all of the light spectrums available from the bulbs listed above, but without the associated running costs or heat generated. They are quickly becoming the bulb of choice as growers learn to adapt to their nuances. That was, however, until LECs or light-emitting ceramics arrived on the scene.


The crux of the matter; what are LEC lights and why are they sometimes called ceramic metal halide (CMH) or ceramic discharge metal halide (CDM)? Thankfully, all terms mean the same thing, and as awareness of the technology increases, these terms are becoming interchangeable. An LEC light uses a ceramic arc tube, rather than the quartz version found in regular MH lights. The result is a more natural colour, producing more lumens per watt and lasting a lot longer. The most common model of LEC fixture is the 315W with a “4200K” colour bulb.

With such stiff competition from LEDs, a seemingly all-round lighting solution, what benefits does an LEC light provide?


For starters, the colour of light produced by this latest development is far more natural. The outcome is, it becomes much easier to see the natural colour of your cannabis throughout its lifecycle. This may not sound important, but it can be vital for reviewing how your plant’s growth is progressing and if there are any issues that can be recognised quickly by changes in colour. As a point of reference, HPS lights give off a very yellow light, while LEDs typically produce a purple hue.

The light spectrum given off by LEC fixtures also provides another point of difference. LEC lights give off UV-B rays,something that, according to anecdotal accounts, improves the trichome production of cannabis during the flowering stage. The result is a perceived increase in yields, however, the verdict on how much it improves yield is still widely speculated. Two more distinct advantages are the life expectancy of LEC lights and their plug-and-play nature. They include built-in ballasts, so setup is very simple. Some manufacturers also claim that LEC bulbs will last up to two years, which is significantly longer than any other options (besides LED).


No lighting solution is perfect, and LEC does carry some disadvantages. The UV-B rays given off are harmful to humans. Adequate safety equipment is needed to reduce any risks to your skin or eyes. At present, the high setup costs of LEC can be off-putting. Because the technology is newer, they cost a lot more than traditional bulbs like CFLs, although this attribute is somewhat of a double-edged sword. The initial cost is higher, but the long-term running costs sit somewhere between HPS and LED bulbs.

They also give off a lot of heat. It is less than HPS or MH lights, but enough to warrant sufficient airflow and cooling options, again potentially adding to the startup cost if you do not already own ventilation equipment. Another consideration would be the positioning of LEC lights versus an HPS lamp. LECs don’t quite match the same light intensity of HPS varieties, so you would need to position the fixture closer to the canopy of your cannabis crop. Lastly, glass blocks UV-B rays given off by LEC bulbs. Growers would need to rethink any obstructions between the lights and plants.


The benefits of LEC appear to outweigh most of the negatives. Improved yields with fewer watts combined with UV-B rays and reduced running costs, the only real contender to LEC is LED. While LEDs offer similar benefits without the addition of excess heat, they cannot currently match the improved yields LECs offer. If you plan to grow cannabis well into the future, you will see a return on investment with LEC fixtures. Should your HPS or MH setup give up the ghost, now may be the perfect time to invest in newer, more efficient technology.

  • Are you searching for cannabis seeds? Check out our seed store – well worth checking out!