Benefits of Sunlight Vs. Grow Lighting for Cannabis Plants

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The longstanding debate continues to rage about whether indoor controlled-environment cannabis grow lighting or outdoor cannabis utilizing natural sunlight is superior. Each camp has its firm and devoted legions that have already made up their minds.

Fortunately, there’s room for both cultivation methods in today’s cannabis space, and one method is unlikely to replace the other. Cannabis requires full sun or artificial radiation to thrive—it’s not a plant that enjoys a lot of shade. It soaks up the rays and grows at a rapid rate. Both natural sunlight and artificial grow lights have their pros and cons. Each is superior to the other in specific ways. Let’s break these down and shine a light on which method will suit your needs best, if that’s an option in your home state.

Natural Sunlight

There’s no replacement for Mother Nature. Sunlight has served the needs of our planet for millennia and shows no signs of letting up anytime soon. Since the cannabis plant does its best with 10 to 12 hours of direct sunlight per day, it soaks up a tremendous amount of solar energy. Access to full, unfiltered sunlight should be the goal of all outdoor cultivators. Sunlight also has the advantage on operational costs since it’s free—and nothing is cheaper than free.

Because cannabis enjoys direct sunlight to grow to its full potential, prolonged periods of shade are undesirable. Commercial cultivators will want a cleared, open field for their grows. A private grower may face more challenges in this area, because unobstructed, 180-degree sunlight can be difficult to provide in a home environment unless the grower has flat roof access or a very large yard. In the Northern Hemisphere, the sun sits in the southern sky. Summer sun—the primary growing season for cannabis—provides advantages because the sun is higher in the sky than other times of the year and the daylight periods are longer. Equatorial sun always stays directly overhead and shadows never grow longer, which is why these areas are well-suited for cannabis. Growers in the U.S. should situate their gardens on south-facing areas for full sun access. Sloped terrain can provide advantages because the cultivator can create a tiered arrangement with rows of plants that have a superior angle for sunlight—as close to equatorial sun as possible in the Northern Hemisphere. Avoid north-facing cultivation sites, because more shows will result, and this is less advantageous for plants.

The sun provides plants with natural full-spectrum lighting that grow lights mimic. The solar radiation that plants rely on for growth is ultra-violet (UV) illumination, a combination of UVA and UVB rays. Plants use and benefit the most from the longer UVA rays. Grow lights do a good job replicating the full-spectrum lighting of the sun for indoor grows. And although it’s difficult to improve on Nature, it’s much easier to control grow lights than outdoor sunlight.

The Uncontrolled Growing Environment

Sunlight can get blocked out by clouds, causing prolonged periods of darkness, which is less than ideal for cannabis. The outdoor growing environment that relies on the sun can also experience periods of wind, rain, and hail, all of which can damage plants. Pests can be another problem outdoors. Deer, rodents, and other animals have been known to devour and damage cannabis, which can have a devastating effect. Insects can be an even greater problem. Some insects and their larvae will decimate lush cannabis flowers to the point that they’re seriously damaged and nearly useless for human use.

These types of uncontrollable variables with outdoor, sunlight-dependent cannabis grows is part of the risk factor that makes some growers opt for indoor cultivation using artificial illumination.

Grow Lights

Plants grown indoors using grow lights must rely on man-made full-spectrum lighting. The most common types of lights used for this purpose are high-pressure sodium (HPS), metal halide (MH), and light-emitting diode (LED) lights.

Metal halide lights emit a whiter light than high-pressure sodium and have a long history of use with cannabis. By today’s standards they are inferior to high-pressure sodium, but they still have applications for cannabis cultivation, especially with young seedlings and young plants in the vegetative stage that are developing root structure.

High-pressure sodium lights emit yellowish orange rays. This type of lighting does an excellent job growing indoor cannabis, particularly during the flowering stage. High-pressure sodium lights are the variety of light that most cannabis cultivators know and love. They are in wide use today in both private home grows and large commercial grows.

Light-emitting diode lights are relative newcomers to the world of indoor cannabis cultivation. These lights are quickly gaining in popularity. While they are more expensive to purchase than other cultivation lights, refinements in manufacturing them has caused prices to come down. Although they initially cost more, they last longer and they use less electricity so they are less expensive to use over the duration of their life compared to other bulbs. In addition, LED lights are safer because they do not get nearly as hot as other bulbs. These factors have caused LED lights to become increasingly popular.

These three popular indoor cultivation lights come in a variety of wattages and designs. The hoods used to maximize their effectiveness vary tremendously. Some have a vertical, domed look, while others have a flatter, horizontal appearance. The most popular wattages are 200, 400, 600, and 1000, although other sizes are widely available. The lower wattages are used mostly by home growers, while the larger 1000-watt and higher wattage lights are favored by commercial growers. The electrical output and limitations of the power source must be compatible with the lights used.

The Controlled Growing Environment

One of the big advantages with grow lights and the indoor growing environment is that the cultivator can control his or her artificial environment. Not only can the intensity and distance of the light be manipulated, but the temperature and humidity can as well. The indoor grower can also provide supplemental CO2, which is impractical and ineffective outdoors.

The controlled indoor environment is also free of risks from pests. No animals or inclement weather will adversely affect the grow and harvest, which is so common outdoors. Light intensity and duration stays constant throughout the entire growing period.

Greenhouses: The Best of Both Worlds?

Utilizing greenhouses for cannabis cultivation is becoming increasingly popular. There are many reasons why this cultivation environment makes sense and has unique benefits. Cannabis cultivators can benefit from the best of both indoor and outdoor cultivation when using a greenhouse.

Greenhouses allow growers to benefit from the sun’s natural light, and plants can thrive in a protected environment. Humidity is easy to control and supplement if necessary, and additional artificial lights can ensure daylight conditions occur when desired year-round. Black-out tarps provide a means for creating nighttime conditions whenever desired. There are many reasons why greenhouses make sense for both home and commercial grows.

Regardless of whether you use a greenhouse, grow outdoors and reap the rewards of natural sunlight, or grow indoors and enjoy the peace of mind of a controlled environment, there’s a cultivation method that’s bound to suit your needs. The choice is yours!

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