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How Much Sunlight Does A Weed Plant Need?

December 1, 2021

We know that all things flourish when placed in the sun. The question remains, how much sunlight does a weed plant need?

The first thought that comes to mind is as much sunlight as possible. While you aren't exactly wrong, your list of "how-to" questions should include this one: how many hours of light does a weed plant need.

The main reason we grow marijuana is to see the fruits of our labor once it produces the most beautiful buds. Getting enough sunlight is one of the key sources it needs to do so. Being clued up about it can only be beneficial to you and your crops.

Below we’ll discuss this further and determine how much sunlight plants need so that you can enjoy the finer things in life. Knowing your cannabis crops are getting the right amount of sunlight, just the way they like it. 

Let's go!

Cannabis outdoors in sunlight
Cannabis outdoors in sunlight

Why does weed need sunlight?

Given all the benefits the sun-grown cannabis receives from sunlight, growers can walk away with a bountiful yield at harvest time. The natural rays maximize plant growth, encouraging quality buds.

The best part of the sun-grown weed is that it produces higher-quality marijuana and fatter buds with better taste.

The chlorophyll in the leaves absorbs the energy from the sun. This process breaks down water and carbon dioxide molecules that produce the energy necessary for the plant to grow.

How much sunlight does a weed plant need a day to receive this energy? Up to 12 hours is sufficient. Sunlight is an important energy source needed to develop healthy roots, branches, and crops.

Those pretty leaves on a marijuana plant are one of the main reasons this crop needs the right amount of sunlight. They have a large surface area, which means enough sunlight absorption needs to take place.

Can weed grow without direct sunlight?

Direct sunlight is by far the most effective way to fulfill the lighting quota of your marijuana plants. Can weed grow without direct sunlight? The answer is complex.

Understanding the difference between direct sunlight and reflected sunlight is essential. At times, growers cannot cultivate their crops in open spaces.

In this case, you may divert sunlight to your sun-grown cannabis by using a reflector.

With an outdoor grow in partial shade, the crop still seeks the sunlight and can develop long awry branches. The development of the bud is compromised, the yield is less, and so is the resin.

Weed can be grown without direct sunlight, with caution.

How does sunlight differ from artificial light for cannabis plants?

When cultivating marijuana, both lighting methods are optional. It all depends on grower preference.

Whether you choose to use artificial ones indoors or rely on the natural rays, one constant question remains: how many hours of light does a weed plant need? No matter the difference between them, cannabis crops still need the right amount of light to feed their growth.

Let's compare the two in a brief outline:

SunlightArtificial light
Free—uses UV illumination from the sunNot free—uses fluorescent, LED, and HID lights
Used for outdoor growingUsed for indoor growing
Uncontrolled lighting exposureControlled lighting exposure
Provides plants with natural full-spectrum lightingMimics full-spectrum lighting
Sun-grown cannabis does well with 10–12 hours of sunlightCannabis grown with artificial lights needs up to 18 hours of exposure
Weed outside
Weed outside

How much sunlight does a weed plant need?

Several factors determine how much sunlight you should give your weed. How much sunlight does a weed plant need a day is one of them.

It would be quite interesting to compare how different autoflowering and photoperiod strains react to the different amounts of sunlight each needs. 

Let's discuss a few of the most common factors which can help us determine this.

For photoperiod strains

Photoperiod strains are standard feminized seeds that are sensitive to light cycles. How much sun does this marijuana need?

Photoperiod seeds have two phases in their life cycle which can help answer this question:

  • Vegetative
  • Flowering

During the vegetative phase, crops require about 18 hours of daily sunlight. During this stage, the weed starts developing its roots and branches only. 

For the sun-grown cannabis to progress to the flowering stage, sunlight absorption requirements drop to 12 hours daily. It's vital to know that the other 12 hours of the day, the marijuana plants need to be in uninterrupted darkness.

The crops remain in the vegetative stage for as long as it gets 15 hours or more of sunlight per day. These plants need "short days" with a lot of sunlight and "long nights" with darkness. 

For autoflowering strains

It's rather amazing how opposite autoflowering strains are to that of the photoperiod ones. How much sun does this marijuana need? As much as possible.

These wonder seeds can receive as much as 24 hours of continuous sunlight. There’s no such thing as too much sunlight for autoflowering seeds.

Growers favor autoflowering cannabis strains, which have become popular sun-grown cannabis because they can be grown in almost any condition. It also doesn't need uninterrupted hours of darkness for it to start its flowering process.

These crops grow to produce bushier buds with a much better yield, provided that it receives the right amount of sunlight.

How many hours of light does a weed plant need per day?

How many hours of light does a weed plant need a day? In a worst-case scenario, marijuana plants generally require up to 13 hours of light per day

The correct amount of light that crops thrive on for growth are:

  • Vegetative stage: minimum of 18–24 hours per day 
  • Flowering stage: minimum of 12 hours per day

The amount that weed plants require depends on a variety of factors:

  • Seed type 
  • Location of seedlings
  • Stage of growth that your cannabis plant is at 

How much direct sunlight does a weed plant need

Do you wonder how much direct sunlight a weed plant needs per day? Cannabis crops are happiest when they receive the right amount. 

Weed plants should receive 10–12 hours of direct sun daily. No problem if your crops aren't growing in a space where it doesn't receive direct sunlight. Make sure that it receives approximately 6 hours of uninterrupted reflected sun.

Can weed grow without direct sunlight? If crops don't receive any UV rays (directly or reflected), they grow slower and provide smaller yields. Get rid of branches and any obstruction to enhance light exposure.

Marijuana outdoors
Marijuana outdoors

What's the difference between sunlight in the equator and the hemispheres?

Are you curious about how much sunlight plants need when grown close to the equator? Your location on either hemisphere is crucial since your location impacts how your crops grow. 

Being close to the equator and receiving the sunlight from either side of the hemispheres influences the amount of outdoor plant light received by cannabis crops. When the Northern Hemisphere is closest to the sun, it's called the summer solstice. Growers in this region experience their summer in June. 

The germination of your sun-grown weed seeds should be between the start of spring in early March and summer. In the Southern Hemisphere, the earth faces the sun in December. Growers should start cultivating their seeds in early September.

How many hours of light a weed plant needs is usually not a concern for growers who live near the equator. Sun-grown weed flourishes at the equator, offering cultivators the opportunity to grow crops year-round. 

The positioning of the equator from the sun never changes. It remains at the same distance, which means it gets 12 hours of sunlight daily. That's music to a grower's ears.


Knowledge is power. The information regarding marijuana cultivation is vast. While we have covered some of the most important facts, some frequently asked questions are common amongst growers.

Can weed plants get too much sunlight?

With the keyword being sunlight, the answer isn't quite simple. Sun-grown cannabis thrives on the energy it receives from the sun to grow, so that's a no. Considering the strains that need darkness to flower, too much sunlight would be a yes. 

Do weed plants need light or heat?

Your sun-grown weed needs both. Sunlight is a source of light and heat. It's important to remember that since your crops need a lot of sunlight to grow, it's also receiving heat simultaneously. Keeping the temperatures regulated is a must for cannabis cultivation. 

How long can weed plants go without light?

It's dependent on the strain you’re growing and your sun-grown cannabis plant's growth stage. It can't go without light for extended periods. The longest your crop can go without uninterrupted light absorption is 24 hours. It won’t die instantly but may become stressed.

Weed under sunlight
Weed under sunlight

Sun nourished weed!

Who knew that so many intricate details go into growing weed. It makes harvesting those buds a proud moment. Knowing how much sun marijuana needs helps you to optimize your crop's yield.

The amount of sunlight that your crops receive depends on various considerations that might seem minor but play a vital role. 

A question like how much direct sunlight does my weed plant need daily guides you with the decisions you need to make to sustain a generous yield.

There are multiple lighting options available to grow your weed, but direct sunlight is still the best one available.

Now that you've learned about the amount of direct sunlight marijuana crops need, why not put your newly acquired knowledge to the test? Head over to Homegrown Cannabis Co. and check out the wide selection of seeds available.

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