Growing Cannabis – Where to Start

If you are just starting out growing cannabis indoors, there are some things to consider when choosing to buy LED grow lights onlineThe first thing you need to ask yourself is how many plants do you plan on growing. This will tell you which light or combination of lights that will be needed.
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How Many Plants Can I Grow?

Growing Cannabis Plant ChartTo find out how many plants you want to grow, you need to determine the amount of space you have or want to work with. Indoors, the average amount of space per adult plant will be 2.5 square feet. This can vary based on the strain you plan on growing as well as the method you intend to use for cultivation.

For example, if you intend on growing cannabis like a Sativa-dominant hybrid with the ‘screen of green’ (SCROG) method you will need a bit more space since Sativas grow larger and the SCROG method redirects the growth of the plant more outward than upwards.
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How Much Power Do I Need?

So once you determine your area by the number of plants you want to grow you need to determine the total wattage of light(s) that you need. For optimal growth, you will need 50-60 watts per plant so 1 plant = 50 watts. 2 plants = 100 watts, 3 plants = 150 watts, and so on.
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What is a Footprint?

Par Footprint MapThe next thing you need to look at is the area the light can cover also known as its footprint. Standard 300 watt grow lights for cannabis will cover an average of 4 square feet, a 600 watt will cover 5 square feet, a 900 watt will cover 6 square feet, and 1200 watt will cover 7 square feet.
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The area is measured by placing the light at 18-24″ of height above a flat surface or your proposed canopy. Please note that footprint for higher powered lights are larger because the light needs to be placed further from the canopy to prevent bleaching of leaves.
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The spectrum of light will be most concentrated directly underneath the light and as you look further out, you will see the light dissipate. The region that is receiving adequate light is what’s representative of the lights footprint. Anything outside of this range is not getting enough light to grow cannabis to its full potential resulting in a lower yield.
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If you attempt to grow in these outer areas, you will see a lot of stretching or there will be little growth at all. When the plant is stretching, it is focusing its energy on growing towards the light instead of other more important functions like building strong roots, stem, branches and ultimately bud production.
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Can I Get More Light?

There are ways to redirect some of the lost light at the wider angles back onto your plants’ canopy like using the mylar in a grow tent, mirrors, and reflectors on grow lights which can make a significant difference in growing cannabis. This is mainly to be taken into consideration if you don’t have enough coverage from your light or if you want more light in the outer areas.
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What Are PARs?

Grow Light for Cannabis SpectrumPAR measurements are the most important factors in determining a LED grow lights usability but there seem to be many different schools of thought when it comes to the intensity of light needed for growing cannabis. You will see the term PAR addressed by many LED grow light manufacturers which reference the intensity of light but this unit, though most important can be a little bit misleading.
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This is because of the use of secondary optics which focus the light at a lesser angle. By reducing the angle the PAR is increased resulting in a higher measurement. The only problem with this is it reduces to footprint significantly. So, the higher the PAR is not always better.
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Is The Color Of Light Important?

The type of light produced is very important when growing cannabis plants. The two most utilized colors for photosynthesis are Blue (430nm-450nm) and Red (640nm-680nm). Other colors like yellow and green help aid in the plant’s architecture but most of which is reflected.
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Experts suggest you split the light concentration for the vegetative stage to 40% Blue and 60% Red and for flowering stage, 30% Blue and 70% Red. This allows optimum growth for both stages of the plant’s life cycle. This change in spectral output can be accomplished by a veg/bloom switch, a dimmer on your chosen light, or with the addition of another light.
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Full Spectrum Lights

Color Spectrum for Growing CannabisThere are lights that produce what’s called a ‘full spectrum’ and these lights are excellent in that they produce a light that is more similar to the sun. Though not mandatory, it’s always a good to get as close to the sun’s spectral output as possible because that’s what the plant has evolved to absorb.
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Conclusion

So, what have we learned? First, we determined how many plants we wish to grow, then we figured out that each plant will take up an average of 2.5 square feet of space. We also learned to look at the area or footprint of the light to determine whether it might be a good fit for the number of plants we intend to grow.
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Something else we learned that a lights PAR measurements can be misleading depending on whether or not the light has secondary optical lenses. Lastly, we learned that full spectrum lights are good but not mandatory for growing marijuana and blue and red spectrums of light are what plants utilize most.
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If you need any ideas on which lights are among the best, I recommend that you look at the grow lights for cannabis that I have tested and reviewed here. I definitely have one that will work for you and your specific needs whether you are growing cannabis, fruits, vegetables, or house plants. If you don’t see what you like just leave a comment at the bottom of the page and I’ll find a light for you that’s within your budget.
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If you have any questions or have any comments on the subject, please leave your question or comment below and I will respond right away. Thank you for visiting and I’m glad to be able to help you.
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14 Comments

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  1. Good evening Karl,
    Thank you for your detailed reply to my comment.
    We are considering to add some LED light to our little nursery. I also believe that Marijuana is good for medical use, sadly in the US in many states it is not legal yet. I just heard that in Canada they send it by post but I do not know if the quality is very good. I will wait patiently for my plants to grow.

    Wishing you a happy and healthy 2018

    Regards, Taetske

    • I think adding additional lighting will help your plants tremendously with larger growth and bigger yields. I have read some good and bad reviews about the Canadian cannabis that is delivered via post. The one company who has a logo like Walmart is very cheaply priced of low quality the remaining one that I know about sells quality cannabis but it is expansive. I’m guessing you get what you pay for. However, to me there is no substitute for cultivating your own marijuana. It is a very satisfying and rewarding experience and you definitely get out what you put into it. I wish you much success with your nursery and if you need any help, come back and visit me anytime. Have a Blessed 2018!

  2. Taetske

    Good afternoon Karl,

    I live in the south of Spain and there is hardly a day where the sun goes missing. The Spanish authorities allow 5 plants for home use and we have put seeds in 5 pots. Some are doing well but others do not. While the plants are growing we take CBD drops every day, I even give it to a sick pet. I now wonder if it would be a good idea to add this LED lamp to the sunlight. The pots are standing in a window on the south side. What can you advise?

    Regards, Taetske

    • Karl Hosch

      If they are facing south that means they are getting direct sunlight most of the day so you don’t necessarily need to add more light. But if you want to get more growth and higher yields out of your plants you can extend the daylight by adding an LED grow light. By giving your plants an extra 4 hours of light you can definitely expect noticeable results both in growth and yield. If you have 5 plants total I would go with 2 300 watt lights. Having two would allow you to get full coverage over the canopy with ample light. 18-24″ of height would be ideal. They are definitely amazing plants that are know cures and remedies numerous ailments. It’s very hard to understand why it should be illegal. But soon it will be, the governments of the world just have to figure out how to tax it best. Anyways, I hope I answered your question, as far as the lights go I have several to choose from and I’m positive any one of the 300 watt lights will suit your needs. Best of luck to you and come back and see me if you have any more questions. 

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