How Much Light Do Weed Seedlings Need? | Our Ultimate Guide With FAQs!

  • Home
  • Blog
  • How Much Light Do Weed Seedlings Need? | Our Ultimate Guide With FAQs!

by Morgan

Last update:

August 29, 2023

How To Choose The Right Lighting For Your Marijuana Grow Room

Growing cannabis seedlings is a daunting task for a newbie. To increase the chances of success, it is important to know the basic requirements of growing cannabis plants, especially the cannabis light schedule.

The first step in growing weed plants is choosing the right cannabis strain and quality cannabis seeds, which means selecting a strain with a high THC content. Another important factor is the time of year you are planting your cannabis seeds. When you decide to grow weed plants, you need to decide whether or not you will be growing outdoors or indoors.

When deciding how to grow weed indoors, consider this: you can only control four variables, including light intensity and duration, temperature, and humidity. However, you can control outdoor pot plants using different techniques such as providing all the nutrients using fertilizers and watering. But whatever method you choose to grow your weed seeds correctly depends on your experience level and gardening knowledge.

🌿  Join my "growing" community 
of 5000+ happy
cannabis farmers! 👩‍🌾

Receive my weekly articles in marijuana growing,
from seeds to smoke! 
— Morgan, 420GreenThumb 🌱

Here we will discuss the cannabis light schedule an how much light weed seedlings require.

Do Weed Seeds Need Light to Grow (Indoor)?

All cannabis plants require a source of light to grow. But if there is only one light source, it should be a high-intensity light with a full spectrum light. The higher the intensity, the better. If you are growing outdoors, you can use a combination of sunlight and artificial grow lights to achieve the required amount of light for your plants.

plants by the window

For indoor marijuana seedlings, you will need one or more fluorescent lights (4'x4' is ideal). Fluorescent lights are usually used for growing weed indoors because they emit a high amount of light, which is necessary for weed seeds to grow, especially in the vegetative stage.

The wattage rating for the fluorescent lights depends on how much space your marijuana seedlings will occupy in your indoor garden pot. The higher the wattage rating, the more powerful and intense the lighting your pot plants will receive during their growth stages.

The number of hours that each fluorescent bulb should be on depends on how many seeds you have planted and what stage they are at. The best way to determine how long a bulb should be on is to observe the color of the light your plants receive when the bulb is turned off. If it's blue light, turn the lights off for about 15 minutes and then turn them back on for five minutes. If your plants are not receiving sufficient light, increase the number of bulbs you have installed by one or two per pot.

seedlings under the lights

How Much Light Should I Give My Seedlings for Optimal Marijuana Light Schedule?

When weed seed sprouts, they need bright light to grow. Most indoor marijuana seedlings require as much as 1,000 watts per square foot of space. This is why all-white fluorescent lights are the best for growing weed seeds.

However, there are a few situations when you may want to use other types of lighting to provide your marijuana seedlings with the proper amount of light. For example, if you have one or two weed plants in a small pot and are not receiving enough blue light, you can use a low-wattage bulb that doesn't emit much light to help them grow faster.

Another situation is when your plants are flowering and have been growing for a couple of weeks or so, and they experience stunted growth because they don't receive enough cannabis light at the flowering stage. In this case, you can use high-wattage bulbs to speed up their growth again.

Do I Need to Use a Special Marijuana Light Bulb for Growing Weed?

No. You can use any light bulb that emits the amount of light your seedlings need for optimal growth. For example, if you want to grow many plants in a small space, you'll need a high-wattage bulb with as much light as possible. It is also important to know the amount of light your plants need in the seedling stage. On the other hand, if you want to grow only one or two plants in a large pot, you will only need low-wattage bulbs. This is because too much light might affect your plants' vegetative stage.

a plant under the light bulb

How Long Should I Keep My Marijuana Plants in the Dark After They Are Finished Flowering?

The ideal time to remove your marijuana plants from their lights is when the nodes on their stalks have stopped growing, which happens after a few weeks of flowering. However, you can keep your plants in the dark for a little longer if you want them to continue growing and get bigger.

This is especially true if your marijuana plants have been growing for a long time without getting enough light. You can keep them in the dark for four weeks after they stop growing new nodes. If you keep them in the dark longer, you might see some side effects from not receiving enough cannabis light during the vegetative stage and growth.

You will notice that your marijuana plant's stalks begin to grow faster once they are getting optimal cannabis light schedule again. When this happens, it's time to put your plant back under its light again. It would be best if you also tried to keep the plant in a bright room with good ventilation. The less light your marijuana plant receives, the more it will start to grow.

closeup of a light bulb

What Kind of Lights Should I Use for My Marijuana Plants?

It would help if you first used low-wattage bulbs for your marijuana plants. You can purchase these at any home improvement store or local hardware store. However, it would be best to never use high-wattage bulbs for growing weed plants because they will burn them. You can also purchase grow lights at most gardening stores that contain metal halide or LEDs. These are both very efficient lighting options, and they come in many different sizes and wattages, so you can find one that fits your needs perfectly.

How Often Should I Change the Light Bulbs for my Grow Lights?

It would be best to change the light bulbs for your grow lights at least once a month. This will give your plants enough time to adjust to the new light bulb. If you are unsure when to change the bulbs, you can always purchase a timer that will alert you to switch the bulbs. You can also use an old light bulb and put it in a jar during the vegetative and flowering stage.

weed plant under the grow lights

How Far Do LED Lights Need to be From Weed Plants?

The distance between your LED lights and your weed plants depends on what lights you are using.

If you are using LED grow lights that are the same size as your marijuana plants, you should place the lights about four inches away from the marijuana plants.

If you have a larger LED grow light, you should place it about six inches away from your marijuana plants.

What is a Good Temperature for Growing Weeds Indoors?

Most people think that growing marijuana indoors will be easy because they can control all of the temperature conditions in their homes. However, this is not true because many factors affect growing temperatures. You can control the temperature in your home by using air conditioning or fans to cool down your house or by purchasing an indoor hydroponic system that will automatically regulate and maintain the right temperature for growing cannabis plants. The best thing is to find out your ideal indoor growing temperature and then buy a hydroponic system that automatically regulates your temperature.

What is the Light Cycle for Growing Cannabis?

The cannabis light cycle is the amount of time your marijuana plants are exposed to light and the dark. Most indoor growers use a cannabis light cycle with 18 hours of light and six hours of complete darkness. However, some growers will use marijuana light schedules of 12 hours of light and 12 hours of complete darkness. The marijuana plant needs both light and darkness to grow properly, but it is important to maintain a regular marijuana light schedule. So what is light dep?

Light deprivation is a technique where the marijuana plants are placed in a dark room or completely covered by a plastic bag for a certain period. This allows your cannabis plant's stem and branches to strengthen and thicken up before being exposed to the high light intensity during the flowering stage.

cannabis plants in dark and lights

How to Maximize Cannabis Plant Yield?

To maximize your weed plant yield, you should start with a good growing medium. You should also have a proper lighting and ventilation system installed in your grow room. You should also use the right nutrients to ensure enough nutrition for your plants. The amount of light you get will also determine the size of your plants. For example, if you want to get high yields, you should place your marijuana plants under a 1000 watt HPS bulb.

For example, if you want to grow marijuana indoors, you must invest in a powerful light such as an HID light or LED for indoor cannabis growing. However, if you want to optimize the yield per wattage of growing weed indoors, use an LED grow light because it uses less electricity than other lights, such as MH/HPS lights and fluorescent tubes.

Should You Consider Indoor or Outdoor Growing Cannabis Plants?

The answer is yes and no. Indoor cannabis growing is a lot cheaper when compared to outdoor. But, you will be limited in terms of the number of plants you can grow because it is a smaller area than outdoor. Outdoor marijuana growth has its benefits as well. You can start growing at a very young age and have an unlimited supply of cannabis for yourself or your friends and family members. The only drawback with this method is that you need to deal with weather conditions that may be unpredictable at times, so you should consider proper maintenance before starting the process.

🌿  Join my "growing" community 
of 5000+ happy
cannabis farmers! 👩‍🌾

Receive my weekly articles in marijuana growing,
from seeds to smoke! 
— Morgan, 420GreenThumb 🌱

Related posts

About the author 


I discovered the benefits of Cannabis at a young age in 2002, with years of trial and error, my knowledge grew just like my plants. As my love for cannabis unfolded I began to teach and learn, trying to gain as much information and practical growing experience.

  • At the beginning you say pick a strain with high THC content.
    You left out those of us who want CBD rich

    You also said Indoor cannabis growing is a lot cheaper when compared to outdoor.
    I think you have that backwards.

  • {"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}