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How Much Sun Is Too Much For Cannabis?

Last Updated: November 29, 2022By Joshua Mezher


Sunlight contains the perfect light spectrum for growing marijuana, but it is very tricky to control. If you are planning to grow marijuana outdoors, you should understand the importance of sunlight, but you should also understand how much is too much.  

When it comes to growing, there are two types of cannabis plants: photoperiod cannabis and autoflowering cannabis. Both grow well outdoors. Photoperiod cannabis requires an uninterrupted period of darkness to bloom, whereas autoflowering weed requires more light and less darkness to bloom. Autoflowers are also suitable for growing outdoors in areas that do not get plenty of light. This is because autoflowers can flower even when the sunlight is weak. 

Light is essential for cannabis plants. Whether in the shade or sun, marijuana requires light to undergo photosynthesis. This light can be natural, artificial, or reflected.

Importance of Sunlight When Growing Marijuana

Light is essential for marijuana plants to reach their greatest potential. When you grow marijuana outside, sunlight is your light source, and cannabis plants can absorb plenty of it. The cannabis plant’s love of sun is the reason why sunny places such as LA or Vegas are perfect for outdoor growing.  

Here’s why sunlight is important:

  • Sunlight helps marijuana plants produce stems and leaves through the process of photosynthesis. These stems and leaves then play a crucial role in absorbing more sunlight, which is then used for further growth of the marijuana plant.
  • Sun-grown marijuana often produces better yields and higher weed. There is no replacement for the sun. Although soil and water also play a role in cannabis plant growth, they don’t have as big of an impact on your plant’s growth as sunlight does. More sunlight means higher yields.  
  • Sunlight determines the growing season for cannabis plants. When enough sunlight is available year-round, like in the sunny Southwest or Southeast, autoflowering cannabis can be planted several times a year. 

If you are growing outdoors, sunlight will be your primary light source. Alternatively, if you don’t receive a lot of light, you can use a reflector to increase the amount of sun that your plants receive. Reflected sun marijuana still gets the benefits of being grown outdoors. 

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The Benefits of Outdoor-Grown Marijuana

When it comes to the sun marijuana can hardly get enough. The two work together to produce potent buds, and it’s incredibly cheaper than growing indoors. All you need is a little sun, marijuana seeds and a few supplies (which we’ve already gathered for you in our Complete Kit.) Based just on how easy it is, outdoors is simply the best way to grow marijuana.

Here are some other benefits of growing outdoors: 

  • Sun-grown marijuana reduces the marijuana industry’s carbon footprint. Research shows that indoor-grown cannabis consumes as much energy per square foot as a commercial building, which is a lot of energy. Indoor grown marijuana needs to be exposed to light 18 hours per day, and many growers use high-energy artificial lights such as HIDs to replace sunlight. This leads to a large chunk of energy consumption. Outdoor-grown cannabis, on the other hand, uses the energy of the sun. 
  • Sun marijuana produces more while using less energy. When you grow outdoors, your plant will develop larger buds and produce higher yields. You’ll also spend less time adjusting the environment, because other than moving or covering your plants, there isn’t much that you can do to change nature. 
  • Growing outdoors is cheaper. In addition to artificial lights, grow tents, and fans, you’ll also need to maintain steady temperature and humidity levels. This can become costly. However, when you grow outdoors, you do not have to worry about any of these costs. If you live in an ideal environment, you could grow outdoors with just some seeds. However, we recommend using a Pot for Pot for the best results. 
  • Outdoor-grown plants tend to be more durable and boast stronger immune systems. There’s something special about the full-spectrum light that the sun provides, which is probably why marijuana plants love the sun so much. As a result, sun marijuana tends to have higher quality and better taste. These plants are also better at fighting off mold and mildew. 

Related Article: Growing Marijuana: Step-by-Step Guide

outdoor cannabis plant in the sunlight
How Much Sun Does Marijuana Need?

When you grow cannabis, you need to understand how much sunlight your plant will need, but you should also realize that the sun is both a source of light and a source of heat. You want it to be warm enough for your plant, but not too hot. Temperatures between 60°F and 80°F are ideal. 

Under the direct sun, these temperatures can be challenging. In the situation where the temperature gets too high, you will need to focus on cooling your plant down while providing enough light. Manage this by watering in the early mornings (and sometimes the evenings,too) to cool the soil and roots. Sometimes moving the plant to the shade or building a shade structure for the hottest parts of the day can also help. 

When it comes to how much light your cannabis plant will need, it depends on whether it is photoperiod or autoflowering. Here’s an overview of the two: 

Photoperiod cannabis

    When growing photoperiod marijuana strains, you should expose your plants to 18 hours of sunlight and 6 hours of darkness during vegetative growth, and then 12 hours of sunlight and 12 hours of darkness for flowering. The darkness is crucial for your flowers to bloom. Some marijuana strains can survive with as little as 6 hours of sunlight, but it’s a good idea to give your plants more than that. 

    Autoflowering cannabis

      Autoflowering marijuana strains also require a large amount of sunlight, but for a shorter amount of time. Many are ready to harvest within ten weeks, and they begin flowering in their fourth or fifth week after germination. The difference is the amount of darkness. Unlike photoperiod cannabis, which requires an uninterrupted dark period to bloom, autoflowers do not. For autoflowers, there is really no such thing as too much sunlight! In fact, they could receive 24 hours of light, which sometimes occur in Far-north areas like Alaska, and grow larger, bushier buds with better yields as a result.  Though we recommend around 4 hours of darkness each night for autoflowers.

      Related Article: How to Grow Cannabis Using LED Lights

      Is 13 Hours of Sun Too Much for Marijuana?

      If you are talking about autoflowering strains, absolutely not. However, if it is a photoperiod strain, that is okay during the vegetative stage only. You should have more sunlight during the vegetative stage and less darkness to help speed up vegetative growth. But, during the photoperiod cannabis flowering stage, a 12/12 cycle is ideal and the only way to keep your flowering photoperiod plants happy.  If photoperiod marijuana plants are exposed to the sun during their dark hour, their growth hormones will be confused and they may revert to the vegetative stage.

      weed in the sunshine

      So, How Much Sun is Best?

      Once again, this depends on the type of cannabis that you are growing. Photoperiod cannabis only starts flowering when it is exposed to a minimum of 12 hours of uninterrupted darkness each day. After they bud, you must continue providing them with long nights until their harvest, or they might go back to the vegetative stage.  

      Outdoor photoperiod plants start flowering late in the summer when the nights get longer, and the days shorten to less than 12 hours of sunlight. This is why it is vitally important to make sure that photoperiod plants are not exposed to light during the night. Even things as common as streetlights or spotlights can interrupt the flowering stage. If this happens, your plants may revert to the vegetative stage, or even worse, become a hermaphrodite, which could lead to it pollinating your other plants and ruining your grow.

      With autoflowering varieties, the outdoors is the perfect solution for providing all of the sun marijuana needs. It will happily soak up as much as you can give it, you just need to make sure your plants have at least 2-3 months of warm, sunny weather. If you can’t promise this, don’t worry, some autoflowering strains thrive in cold weather. However, when autoflowers are exposed to too much sunlight, they have bigger and better yields. 

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      How to Grow Marijuana Indoors Without Sunlight

      If you cannot guarantee enough sun for your plants, you should consider growing them indoors. It’s easy to grow marijuana indoors, as long as you provide enough light and keep it from getting too hot. Similar to outdoor plants supplemented with some reflected sun, marijuana grown with an artificial light source can thrive just fine. For many people, the largest struggle is finding enough space, as some cannabis plants can grow quite tall. However, with autoflowers and other small stature strains, growing a single plant indoors isn’t that crazy of an undertaking. 

      Getting started on an indoor marijuana garden is not that hard, as long as you make sure you have all of the necessary equipment. This includes:

      • Grow tent (optional)
      • Containers for planting
      • Soil or another growing medium
      • Grow lights
      • Air conditioner (optional)
      • Exhaust fan (optional)


      a Pot for Pot can provide the soil, container, grow light, and other accessories. 

      Then follow these instructions: 

      • Make space for your new plant. Ensure there is plenty of airflow. 
      • If you are using a grow tent, construct it, and set it up in your space. Grow tents are ideal if you are growing multiple plants. Make sure that the tent that you choose is big enough for your plants and any equipment that you use. There should be plenty of space for air to get around. If you are growing a simple plant, you should place your plant near a window so that it receives some light and add a grow light to help on cloudy days. 
      • Install your grow light(s). There are many options in lights for growing marijuana. If you are growing a single plant, a Light for Pot is an easy solution. This attractive and easy-to-use light is LED, which is a favorite among home growers. LED is energy-efficient and won’t get too hot like other options.  Lastly, make sure that your grow room is tightly sealed to prevent any light from leaking. 
      • Make sure that your grow room has adequate air circulation. Fresh air is essential for your plants to thrive, and CO2 is crucial for the process of photosynthesis. If you are using an exhaust fan, place it near the top of your tent. It will help move hot air to the outside; however, be sure to use a carbon scrubber with it, or else everyone else will smell what you are doing.  

      • You’ll also need to keep the grow room temperature between 70-85°F when the lights are on. When the lights are off, the temperature should be between 58-70°F. (Keep in mind, indicas tend to like it cooler). The growing space’s temperature should be a real consideration, especially if you grow a lot of plants. Multiple plants mean multiple lights, and those lights can pack some serious heat. You’ll want to buy a larger exhaust fan if you are working with multiple plants. You may also consider purchasing an air conditioner.  

      If you are growing photoperiod plants, you’ll also need to change the light cycle to mimic the change of seasons that your plant would experience outdoors. When your plants are seedlings or clones, they require 18-22 hours of sunlight per day to promote faster vegetative growth. This is when they should be receiving the most light; the amount of light that your plants receive should be greater than the amount of darkness. Once the plant is large enough to transition to the flowering stage, photoperiod cannabis requires at least 12 hours of light and 12 hours of darkness each day. This is when too much light becomes a problem. 

      autoflower under a Light for Pot

      For autoflowers, lighting is a lot more straightforward. You can provide as much light as you like, especially during the vegetative period, but a little dark time is typically a good idea once you reach flowering. And you get bonus points if your indoor autoflower gets some sunshine, too. Don't be afraid to take her on field-trips on nice, sunny days!

      Other than that, everything else about the growing process remains the same. 

      If you plan to grow marijuana outdoors, whether its photoperiod or autoflowers, you need to be ready to give your plants plenty of sun.  If you’re worried about it being too much, it’s probably not, unless you’re actually talking about heat. If that is the case, get your plants in some shade during the hottest parts of the day or your marijuana plants will turn into thirsty, heat exhausted, underproducing cannabis plants. As long as you keep your plants at a comfortable temperature, do not be afraid to take advantage of the sun to produce bigger, more potent (and better-tasting) buds.


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