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Light and How Cannabis Consumes It

In the eons before dinosaurs, plants dined on light.

During the early formation of our planet, there was no oxygen to breath, only water and light. This paradise of water and photons gave rise to the first plants. Not like the orchids and redwoods we are accustomed to today, early plants were mostly algae in the early oceans. These early plants developed a way to transform light into food.
By using sunlight to convert light energy into chemical energy, plants were able to store it for later use. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll pigments.
In plants like cannabis, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells. In the light-dependent reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin and the process propels a chain reaction of life.
cannabis lights

Plants can use light from across the visible spectrum for photosynthesis.

Yet some wavelengths of light are more useful to a plant than others. Wavelengths that the plant uses a lot of get absorbed into its leaves and stem while wavelengths they don’t use get reflected back. We only see plants as green because they don’t use green light energy. They reflect the one color they don’t photosynthesize so we perceive them as green.
Because of how plants evolved their ability to photosynthesize, different wavelengths are needed in greater amounts at certain stages of a plant’s growth, such as the blue and red. Light high in the blue range enhances vegetative growth, while red light strongly influences flowering and fruiting.
What we perceive as visible light is comprised of seven main colors. All the odd colors we see like pinks, browns, and beiges are just mixtures of other colors. Our eyes can only register wavelengths of light are within the 400 to 700nm range. Below 400nm, we move towards ultra violet, x-ray and finally gamma rays. Above 700nm is infra red, then microwave and finally radio waves.

Let’s start with some measurements.

Nanometres (nm) are a measurement of light waves. Each degree in Kelvin (°K) rates the ‘temperature’ of a light and offers an indication to the peak nanometers (nm) or color within the spectrum. The lower the nm, the more blue the light appears while higher numbers look red.
Marijuana uses light from approximately 420nm through to 750nm. But what does that mean? To understand the unique diet of cannabis (and make those real yield gains) we need to create the ideal environment for the plants.
Giving them just any light simply won’t do if the goal is heavy crops (and who doesn’t want that?). Normal incandescent bulbs produce more high energy wavelengths like infra red (heat) and midrange light (550-650nm) than anything else. Anyone who has tried to grow a plant in a room lit only by incandescent bulbs can attest to their poor performance so avoid trying to grow with them.

Even light in the right wavelength may not have the right amount of lumens.

Cannabis need light from the right part of the spectrum with the right amount of intensity to encourage proper yet fast growth. Marijuana evolved to grow under sunlight which changes intensity over the seasons. Young weed plants can be easily burned if put under the same intensity of light as a mature ones.
For this reason, many cultivators use different lighting techniques for the different stages of plant growth. Fluorescent lights produce the right wavelengths for growth but lack the intensity of other lighting options making them the standard for use with seedlings and young clones. HPS (High Pressure Sodium) and MH(Metal Halide) are industry standard lighting options that are used during vegetative and flowering stages although LED (Light Emitting Diode) are quickly establishing themselves as premium lights in the market.
HPS light

There are a few different types of light.

HPS lights offer light from approximately 540 through to 700 nm, typically yellow, amber and red light so they are great for flowering/budding marijuana. These lights tend to burn hot and need to be ventilated as well as hung from a decent distance from the plants. This makes having a tall area to grow in a priority. Luckily, the light produced by HPS lights penetrates deeply into thick canopies which is perfect for the flowering stage when buds and leaves are competing for room.
MH lights offer light from approximately 350 to 550 nm in the blue, green to yellow range.  However exact levels depend on what lamp your purchase as some lamps are ‘cooler’ and others a bit ‘warmer’ than average. MH lights are good for the vegetative stage but not as much for the flowering/bud stage.

Lighting is going high tech.

LED grow lights can have a mix of LED diodes in a single ballast or specialized ones. This gives cultivators one more variable to work with but it also opens up a whole world of adjustment. With the increased lifespan of diodes over bulbs, reduced energy consumption and lower heat production, it is easy to see why cultivators are switching to LED.
While LEDs are far more efficient then HPS or MH lights (with almost 30% savings reported on average) they come with a significantly higher initial price tag. Small projects and weekend cultivators may not want to shell out the cash needed to obtain a quality growing LED but commercial outfits normally opt to go with the reduced energy consumption and quickly make back the difference in initial price.
LEDs also have the benefit of not needing specialized heat venting as they produce almost no heat.  While HPS and MH lights require ducting, fans and additional controllers, LED lights don’t need any of that while providing a dynamic mix of color temperatures. The best LEDs are full spectrum and use some blues, some reds and a very stable white to create broad (full) spectrum LED grow light. These are the new breed of grow light and cover the full light range from around 420 through 750 nm.

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Grow Lights: How to Choose the Right One

It is tempting to believe that there is such thing as the perfect grow light. A single radiant source that simply out performs everything else out there. Such a light does not exist at the moment but we have a few options. Even sunlight (the full spectrum, nuclear powered, plasma-based grow light in the sky) can damage plants if the rest of their environment is not well suited to them. Cultivators have to choose the right grow light for the right situation.
There are a few key considerations when debating between the most common lighting methods available. Using good old sunlight should work if you live anywhere near the equator but for those in the north or south need to rely on artificial means if they want to produce all year. Different growing techniques lend themselves to different setups as well.
Plasma, Induction, Ceramic Metal Halide, there are a lot of variations when it comes to lighting but for todays discussion we will be limiting the conversation to the three most popular methods. The lights we will discuss are easily obtainable, proven effective and utilized across the industry as the benchmarks that all others must compare to. There is a bit of variation within each category but they all function similarly (although you may need more than a wall socket for some).

Cultivators must consider the size of their garden.

Using a 1000-watt grow light in a two-foot by four-foot closet is generally wasteful and can lead to a lot of unnecessary problems like overheating. On the other hand, trying to cover a commercial garden with a 40,000 sq. ft. canopy in Compact Florescent Lights (CFL) won’t produce the same level of production as other lighting methods.
Growers working with small spaces need to prioritize heat dissipation over light penetration. While higher wattage lights provide more energy for your plants to work with, if the heat they produce is too much, it can stunt the plants growth. Using Compact Florescent (CFL) ballasts over High Pressure Sodium (HPS) or Metal Halide (MH) options can reduce heat buildup in small spaces while Light Emitting Diode (LED) ballasts provide a balanced mix of heat and light at a higher price point.
If you are growing more than 2-3 plants and have enough space for dedicated heat exhaust ducting, an HPS or MH light might be the right solution. The extra space needed to process the heat given off by these lights is made up for in high production levels. There are several sizes ranging from 150 up to around 1000 watts and each is designed to cover a different sized area.

Complexity is also a major consideration with grow lights.

There is a lot more to growing dank herb than sticking a seed in the ground and waiting for mother nature to work her magic. Top producers monitor every element of their operation with grow logs and performance metrics. Most growers can get away with going by eye and only measuring when they must but that won’t produce those head-sized colas that win competitions or get featured on the cover of High Times.
Adjusting CO2 generators, maintaining air conditioners and dehumidifiers, setting timers, calibrating sensors and monitoring schedules are all part of a commercial operation and can quickly add layers of complexity to a seemingly simply project. Getting the most advanced or largest lights possible may add extra layers of complexity like running exhaust ports, vent fans and electrical lines.
Having to install an extra circuit breaker is pretty frustrating but having to get the power company to upgrade the lines and transformers heading to your place in order to put in extra HPS lights can run into the tens of thousands of dollars. Using LED lights may have a higher initial investment cost (making quality versions expensive) but the energy savings add up over time.grow light

Budget is always important with grow lights.

Sometimes bigger isn’t better. If all you are doing is looking to offset the cost of buying cannabis, getting a massive light and converting the garage into a clean room worthy of NASA may not be the best route. A low cost (albeit moderate output) closet operation may work better, especially if you don’t consume only the freshest of rosin.
There are tons of options on the market for a small space grow operation with everything in a single kit. The kits normally come with a light, maybe a few pots or hydroponic bays, and they actually work pretty well (in general). They are more expensive than building it yourself but offer significantly higher quality than most people can cobble together on their own. If your goal is to make money, customization is the name of the game.
Installing LED lighting in an industrial in-door grow operation is almost a must. The initial cost is more than offset by the increased operational life of the ballasts along with the drastic (up to 30%) savings on energy. Industrial and commercial operations may still utilize CFL lights for seedling growth given the low overall cost of operating fluorescents.

When it all comes down to performance, a leader emerges.

In the end, we all want the best bang for our buck. CFL’s are great for seedlings/clones but not great for vibrant vegetative/flowering growth. Their low operating temperature also makes using them fairly basic. A low-cost alternative to LED’s for small-scale growers, CFL’s offer a solid base of performance to work up from.
HPS and MH lights offer greater output than CFL’s and are best for medium to large operations. They are specialized to vegetative and flowering and scale well for larger operations. The excess heat HPS and MH light produce compared to other options needs to be dealt with through specialized ducting or increased air conditioning but many ballasts offer specialized ports to make this easier for large strings of grow lights.
LED grow lights offer the highest performance of any grow light option but also come with the highest cost. While they don’t require the ducting of the HPS and MH lights, LED’s provide as intense of a light as any other option.  In addition to being the right intensity, LED’s require far less maintenance with a projected operating life measured in years, not months.

What is your end goal?

We have only toughed on the surface of grow lights and how to choose between them. If you want to get started quickly and easily, look into an assembled unit. It makes all the difference to have a station ready for you and not have to make all the little decisions yourself. Once you get the feel of things, you will likely be able to work with the prebuilt to fit your preferred style of growing until you are ready to do things a little bigger.
If your goal is to make money and you are just getting started, investing in HPS and MH lighting for vegetative growth and flowering along with some CFL may be the right call. Their overall cost is doable and they provide a great end product with a few extra considerations.  This is the most common setup for small to medium indoor growers looking to turn a profit.
If money is no object or you are working on a massive scale, LED lights provide the best returns over time. With minimal energy drain compared to other lights and the low operating temperature makes the energy savings a real consideration. Many units can also provide full spectrum light or specialized wavelengths for different plant cycles making them more versatile than the HPS and MH which must be switched between cycles.
Let us know what you chose to light your garden and why in the comments section. Thanks for reading.