Cannabis cultivators have many options when it comes to cultivation facility lighting, but which are the best?
Of the many variables that go into cultivating a successful cannabis crop, lighting is one of the most important–and costly. We often work with cultivators in the throes of deep cannabis lighting puzzles, so we’ve decided to help.
Here’s a guide designed to help you make informed lighting decisions, so you can grow potent cannabis buds consumers love.
Know What You’re Buying
To make good lighting decisions, it is essential to understand how light is measured. Forget terms like lumens, which tells you how bright a lamp is, or watts, which tells you how much energy is consumed.
While these terms can be helpful, the quality and quantity of light your lamp provides for good plant growth is what’s genuinely important.
Using a PAR light meter, growers can measure photosynthetic active radiation (PAR) from a light source, including the sun. Photosynthetic photon flux density (PPFD) is the standard of measurement in the industry and measures how much PAR reaches the plant surface.
Growers generally shoot for 700-1000 PPFD, although some lights can reach up to 2000 (which is about the PPFD of the sun on a cloudless day). Simply stated, the more quality light for plant growth, the faster the growth and better bud quality.
Another critical factor is the light spectrum.
- Blue light supports growth in the vegetative stage and controls stem elongation, i.e., stretch.
- Red light is more supportive of the flowering stage of development.
Fluorescent lights emit blue spectrum light, so they are suitable for the vegetative growth cycle. High-pressure sodium bulbs (HPS) offer light in the red spectrum. LED lights may come in red or blue; however, for growing cannabis, they come in a combination of blue and red with the option of flipping a switch between vegetative and flowering cycles.
Manufacturers of light fixtures for horticultural applications should be able to provide the PAR values for their products. However, many don’t, so we suggest that you insist on finding one that does; it can be critical to your growing operation.
The LED Advantage
Over the last five years, growers have increasingly turned to Light Emitting Diodes (LED) as their preferred choice, according to a 2021 survey conducted by Cannabis Business Times. The survey found that 62% of cannabis growers use LED lights for vegetative and flowering cycles, compared to 21% in 2016.
LED technology has matured at about the same pace as the lucrative cannabis industry. As a result, today’s LED technology can deliver the same results as HID lighting with much less energy usage. Quality LED lights use less electricity and run much cooler than high-pressure sodium fixtures, increasing savings for growers.
LED lights can be used for both the vegetative and flowering stages.
These lights should be rated for no less than 1000 PPFD. There are a handful of companies out there that manufacture quality LED fixtures for the cannabis industry.
High-Pressure Sodium Lamps
Despite the increase in growers turning to LED technology to grow their marijuana plants, a good percentage of growers are using other types of lighting, most notably, high-pressure sodium (HPS).
HPS lighting has been the gold standard for several years, particularly among hobby growers. However, you should keep in mind that these lamps require changing out bulbs, one for the vegetative stage of growth, the other for the flowering stage.
While they provide full-spectrum light needed in the different stages of plant growth, they consume a lot of energy and run much hotter than LEDs, requiring some type of ventilation and cooling.
A relatively new addition to the cannabis lighting market is the doubled-ended HPS. Unfortunately, these units require a ballast upgrade, and the bulbs are more expensive than the standard HPS bulbs. On the plus side, they’re more energy-efficient than the older style, last longer, burn cooler, and have been shown to increase yields.
T5 Fluorescent Lights
These fixtures are relatively inexpensive and are used only in the vegetative stage of marijuana production.T5 fixtures consist of multiple fluorescent bulbs and emit colors in the blue spectrum of light.
From a commercial cannabis growing perspective, the downside is that you must move your plants from under the T5 units to lamps that provide light in the red spectrum, such as the high-pressure sodium bulbs.
Therefore, these units are better suited for starting clones or small cannabis growing operations.
Measuring Light with a Light Meter
As a final note, it’s essential to obtain a good PAR light meter so that you can take readings in different areas of your grow facility.
This is helpful in several ways.
Using a light meter, you can adjust the height of your fixtures so that the plants get the quantity and quality of light to the leaf’s surface as measured with PPFD readings. If you’re growing under glass or a greenhouse covering, you can also determine if your plants are getting enough light through these coverings or if you need to upgrade them to newer coverings that will emit more light.