Cannabis Questions Answered: What Do You Really Need To Know About Outdoor Grow Lights?


There is something exciting and magical about starting a new grow. This is especially true if it is your first or one of your first. However, even if you have been growing for years, there is just something about starting that new grow. It is like an adventure. A time to discover and uncover something new. That being said, when starting a new grow there are a lot of things that must be taken into consideration. Amongst them, the most important is the lighting. Your nutrients, grow techniques, and water levels could all be dead on, but if your outdoor light is off, you aren’t going to get the desired results. This is why it is more than imperative to understand everything you possibly can about marijuana lighting and how it affects your plants.

Understanding The Photoperiod

In order to get the most out of your grows and your lighting situation, you need to fully understand the photoperiod. Now, do not let this confuse you or deter you from reading any further because it isn’t as complicated or scientific as you might think. In fact, photoperiod simply means nothing more than the amount of light that your plants get during the different stages of growth. By now, you probably already know that most plants get 18 hours of light and 6 hours of dark during the vegetation stages. On the other hand, the flowering stages will be 12 on and 12 off. That’s simple enough, right?

The most important thing to know is that during the plant’s photoperiod, it needs to remain relatively uninterrupted. Frequent and erratic changes are only going to deter the growth of the plant. That aside, there are a lot of growers that like to experiment around with the lighting and lighting stages. Some growers will not only switch up the hours of growth, but they will switch up the types of lights they are using during the different stages. There is nothing wrong with this, as long as these changes are made gradually and slowly. For instance, if you are on a 12/12 period and want to make changes, start with a simple change like 13/12.

In addition to this, you also need to know that cannabis plants have two key photoperiods that can determine how they grow.

The Two Key Pohtoperiods

As you probably guessed, these two key photoperiods are the vegetative state and the flowering state. However, this is where things can get a bit more complex and scientific. The photoperiod controls the stages of the plant’s life. And it does exactly this by relying on a light-harvesting complex referred to as phytochrome. During the day, exposure to red light excites phytochrome and causes it to react. When this complex is in an elevated or excited state it will cause the plant to not flower. Thus the vegetative stage is controlled by keeping the phytochrome excited. This is why plants are exposed to 18 hours of light during the vegetative stage.

Some growers will probably even recommend keeping the plants exposed to outdoor lighting for 24 hours, but plants are like humans in the respects that they also need rest. If you want to bump up your hours, it would be advisable to go no higher than 20 on and 4 off. All that aside, it takes nearly 12 hours for a plant to relax, hence the 12 on and 12 off during the flowering stage. When the plants are relaxed they will produce bud.

Time Is Not The Only Influencer

While you can see that time is crucial when it comes to phytochrome elevation, you need to understand that it is not the only factor. Phytochrome can also be de-energized when plants are exposed to far-red light. This is why some growers will experiment with keeping the light on for 14 hours then exposing them to far-red lights for a short interval of 15 to 20 minutes. When this is done, the exposure speeds up the conversion of phytochrome to its ground state. This all probably sounds somewhat scientific and complicated, but the theory behind it is simple.

The day length extension allows the plant to engage longer in photosynthesis while also remaining in the flower state for an additional two hours each day. This would be an overall 16 percent increase in light, which should yield a 16 percent increase in the crop. It is important to note that specific strains and species will have varying needs when it comes to photoperiods, so it’s best to learn about the specific plant when you are buying seeds.

Sativa strains usually require more lighting during the flowering stage due to the fact that they usually grow in tropical climates where the sunlight is usually perfectly balanced at 12/12 year-round. Indicas, on the other hand, originate in parts of the world where the light is less balanced. On top of this, there are some species known as Ruderalis, which are considered auto-flowering strains and do not need any changes in light at all. They will simply transition on their own without any assistance.

Growing With High-Intensity Discharge Lights (HID)

Most veteran growers are most familiar with high-intensity discharge lights, and this is because they are some of the oldest around. These light usually consist of everything from high-pressure sodium to metal halide. These lights have been utilized widely over the years and will continue to be utilized because they provide the wide color spectrum that cannabis plants thrive on. These lights offer and tried and true method that you simply cannot go wrong with.

Growing With Compact Fluorescent Lights (CFL)

CFL lights are nothing new to the industry anymore and are highly preferred by many thanks to their affordability. These lights give off a full spectrum of light that mimics the sun. The only problem encountered with these lights in the past is that they simply didn’t produce the wattage that was needed for cannabis grows. This is no longer the case at all, as manufacturers have started specifically engineering these lights for grow operations.

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