Does Cannabis Grow Better in Sunlight or Artificial Light?

The longstanding debate continues to rage about whether indoor controlled-environment cannabis lighting or outdoor cannabis using natural sunlight is better.

Fortunately, there’s room for both cultivation methods in today’s cannabis space, and one method is unlikely to replace the other.

Both types of lighting can provide excellent results but generally, sunlight is preferred for better cannabis plant growth.

Cannabis requires full sun or artificial light to thrive—it’s not a plant that enjoys a lot of shade.

It soaks up the rays and grows at a fast rate.

Why Light Is So Important In Cannabis Cultivation

The right type of lighting can improve your marijuana yield, potency, flavor, and aroma.

In particular, the light intensity, light quality, and photoperiod affect how well your plants thrive in their environment.

During different stages of its growth, the cannabis plant requires the production of certain types of chlorophyll.

Chlorophyll is a compound that helps convert light into energy that stimulates plant growth.

The energy they create helps plants absorb water, nutrients, and carbon dioxide from the environment for proper root, foliage, and bud growth.

Sunlight, in particular, contains the full spectrum of light wavelengths for every type of chlorophyll.

During the plant’s vegetative stage, blue wavelengths help stimulate foliage growth. During its flowering period, red wavelengths promote bud production.

Plants that do not get enough light can become stressed and will start to show negative physical signs. For instance, plants may start to turn yellow. Or its leaves may begin to drop or its foliage or bud growth can slow down.

Choosing the right type of light and knowing when to use it can significantly affect the way your plants grow.

Whether you choose to grow indoors or outdoors, you must consider different factors to handle each light source’s characteristics.

Natural Sunlight

There’s no replacement for Mother Nature. Sunlight has served the needs of our planet for millennia.

Since the cannabis plant does its best with 10 to 12 hours of direct sunlight per day during its flowering period, it soaks up a tremendous amount of solar energy.

Outdoor growers should aim for full, unfiltered access to natural sunlight whenever possible.

Sunlight offers a major advantage over artificial lighting when it comes to operational costs — it’s completely free, and nothing beats free.

Sunlight reduces the carbon footprint of your garden.

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 gardens.

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.

The equatorial sun always stays directly overhead and its shadows never grow longer, which is why these areas are well-suited for cannabis.

Growers in the U.S. should set up 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 the equatorial sun as possible in the Northern Hemisphere.

Avoid north-facing cultivation sites, because more shadows will result, and this is less beneficial for plants.

Artificial Lights

Plants grown indoors using grow lights rely on man-made full-spectrum lighting.

The most commonly used lights for growing cannabis indoors are compact fluorescent lights (CFLs), high-intensity discharge (HID) lights, and light-emitting diodes (LEDs).

CFL

Compact fluorescent lights are affordable, accessible, and popular alternatives to the more expensive HID and LED lights.

CFL lights are great for small space gardens, run cooler than other options, and don’t require as much ventilation to maintain the optimal temperature in your garden.

However, CFLs aren’t entirely equipped for the entire life cycle of the plant.

Generally, they emit a lot of the blue light wavelength. That is great during the vegetative growth period. During the flowering period, they do not provide enough of the red hues.

HID

Metal halide lights emit a whiter light than high-pressure sodium lights 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 and don’t need as strong of a light source.

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 gardens and large commercial growing facilities.

LED

Light-emitting diode lights are relative newcomers to the world of indoor cannabis cultivation. These energy-efficient lights are quickly gaining in popularity among home and commercial growers.

While LEDs are more expensive to buy than other grow lights, improvements in manufacturing caused prices to come down.

Although they initially cost more, LEDs 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 run cooler than their alternatives and are safer to use on cannabis plants because they do not get nearly as hot as other bulbs.

LEDs do not require as much ventilation consideration due to their cooling capabilities.

These factors have caused LED lights to become increasingly popular.

Choosing the Right Artificial Light Source

These popular indoor cultivation lights come in a variety of wattages and designs.

The reflective light hoods used to maximize their effectiveness vary tremendously. These hoods are designed to direct the light back onto the plant’s canopy. Some hood options have a vertical, domed look, while others have a flatter, horizontal appearance.

The most popular wattages are 200, 400, 600, and 1000 watts, although other sizes are widely available, depending on your garden needs.

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 the grower can control a variety of factors in 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 and harsh weather. No animals or inclement weather will adversely affect the grow and harvest, which is common outdoors.

Light intensity and duration stays constant throughout the entire growing period with the right automated tools.

One of the biggest advantages of using artificial lights is the ability to grow cannabis all year long. Unlike outdoor growing, growers aren't dependent on the changing seasons.

Artificial light can provide full-spectrum lighting even in the darkest and coldest months.

In an indoor growing environment, however, you must consider how much light your cannabis plants get.

Lighting requirements depend on the stage of growth your plant is in. During its vegetative stage, cannabis plants need at least 18 hours of light per day and 6 hours of darkness.

During its flowering stage, plants need at least 12 hours of light per day and 12 hours of darkness.

Another downside of artificial lighting is the cost of buying and replacing equipment, as well as paying for the energy use.

While there are budget-friendly ways to use grow lights, they are still more costly than growing naturally outdoors.

The Uncontrolled Growing Environment

When growing cannabis outdoors, cultivators must contend with the natural elements and their region’s unique climate.

Sunlight can be blocked by clouds, leading to extended periods of low light, which is far from ideal for healthy cannabis growth.

Outdoor environments also expose plants to heavy winds, rain, snow, and hail, all of which can cause significant damage unless the plants are protected by a greenhouse.

Seasonal changes are another factor outdoor growers must consider.

Longer daylight hours in the summer promote growth, but shorter days in the winter limit the availability of natural light, making year-round cultivation nearly impossible without supplemental lighting.

Pests present another major challenge. Animals like deer, rodents, and other wildlife can eat or trample cannabis plants, severely impacting the crop.

Insects and their larvae can be even more destructive, sometimes devastating cannabis flowers to the point that they become unusable for human consumption.

These uncontrollable variables — including weather, pests, and seasonal light cycles — are some of the key reasons why many growers choose indoor cultivation under artificial lighting, despite the higher energy costs.

Controlled environments offer more predictability and protection, leading to greater consistency and higher yields.

Greenhouses: The Best of Both Worlds?

Utilizing greenhouses for cannabis cultivation is becoming increasingly popular among home and commercial growers.

There are many reasons why this cultivation environment makes sense and has unique benefits. Cannabis growers can benefit from the best of both indoor and outdoor cultivation environments when using a greenhouse.

Greenhouses allow growers to benefit from the sun’s natural (and free) light.

In addition, cannabis plants can thrive in a protected environment that isn't as vulnerable to the whims of the natural elements (temperature, humidity, pests, etc).

In a greenhouse, humidity is easy to control and supplement if necessary.dditional 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 climate-controlled environment, there’s a cultivation method that’s bound to suit your needs. The choice is yours!

Learn More on Does Cannabis Grow Better in Sunlight or Artificial Light at CTU Online

There is much more to learn about the growing of this amazing and therapeutic plant. Whether you’re growing indoors or outdoors, the right type of cannabis education can help you optimize your garden to achieve high yields.

If you’re interested in growing high-quality cannabis in any environment, you can learn all about the process at the world’s leading cannabis college, Cannabis Training University.

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Luis Cordova

Luis Cordova is a distinguished author, and renowned expert in cannabis cultivation, who possesses a Master's degree in Plant Biotechnology and Pharmaceutical Science. As a valued contributor to highly esteemed publications such as Cannabis Training University and Maximum Yield Magazine, Luis has emerged as a trusted source of guidance and knowledge in the cannabis industry. Having written thousands of informative articles, Luis is widely recognized for his comprehensive expertise on cultivating cannabis, both indoors and outdoors.