Step One: How to Build the Perfect Indoor Grow Room (For up to 6 Plants)

January 26, 2018

How to Build a Grow Room - Step by Step Guide

By Ayad Maher


This post, the first part out of 4, is for those you'd like to start growing their own weed. If you were hoping to get into commercial marijuana growing, this can be where you want to start, but eventually you have a lot more work, learning and reading ahead of you.

The first thing you want to do before you start growing is to build the best possible indoor grow room. Your marijuana grow room is where all the fun is happening, so it's very important to plan ahead, taking in consideration your budget, location and every possible problem you may encounter during the growing process, from seeding to harvesting. Many factors you need to be aware off and consider when you setting up your grow room for the first time. 

In this article, we will walking you through building your first indoor marijuana grow room and make sure you're aware of the obstacles you may run into. 

A successful indoor growing can be pricey and need extensive planning to cover your bases. However, once you get your grow room up and going, and once you start growing your marijuana plants, your return on investment will be highly rewarding, financially, emotionally and even socially.

If you don't want to go through the building of your grow room, there are some plug and play options for you.

If you're not convinced yet, check our 5 Reasons Why You Should Grow Your Own Weed, and you will be!

1. Hydro or Soil for Your Indoor Grow Room?

The first thing you wanna do is to decide whether you want to go with Hydro or Soil. Both require different systems, setups and technologies. Although growing hydroponically can take less space. On the other hand, if you were planning to plant only 6 plants, space won't be an issue anyways. Also, using hydroponic systems can be a little pricey and complicated since the marijuana plant is solely relying on you to provide it with everything it needs.

For the sake of the purpose of this post, to provide the easiest and most straightforward techniques to grow marijuana for beginners, we will focus simply here on soil. If you'd like to know more about the difference between Hydro or Soil, check this article from Super Soil #1: Soil vs. Hydroponic Systems. Also, check the video below. 

As for the recommended type of soil, there are too many recommendations out there, but to make it easy for you, we did our research and found out that FoxFarm Ocean Forest is the one for you, it's a soil product that commonly used, and recommended, by professional growers. It's available throughout the U.S. The manufacturer advertises their product as "safe to use right out of the bag and good for seedlings."

As you move forward and grow then harvest your first crops, you will read and learn more about all type of soil, you can even create your own mix, but for the time being, FoxFarm Ocean Forest soil will do the job. 

2. Which Nutrients Should You Be Using?

To growing high-quality marijuana buds, you will have to pay attention to the fertilizer, or nutrients your marijuana crops need. There are two type of macronutrients (primary nutrients); the mineral nutrients, such as:

  • Nitrogen (N)
  • Phosphorus (P)
  • Potassium (K)
  • Calcium
  • Magnesium
  • Sulfur

And in smaller quantities, your cannabis crops will also need the following nutrients: 

  • Zinc
  • Iron
  • Manganese
  • Molybdenum
  • Chlorine
  • Cobalt
  • Silicon
  • Boron
  • Copper

And Non-mineral nutrients, which you don't need to worry about because the marijuana plant derives them from air and water, such as Carbon, Hydrogen and Oxygen.

And in smaller quantities, your cannabis crops will also need the following nutrients: Copper, Iron, Magnesium and Calcium.

If you're going to use pre-fertilized soil mix, FoxFarm Ocean Forest , you want to feed your crops once a week using the proper nutrient solution.

It's recommended different nutrition products for every stage of the cannabis growing process. We will touch on them, and how often feed them to the plant once we get there in our next post. 

3. Find a Place for Your Grow Room

First, we need to find the perfect indoor grow room; a discrete and private place for your marijuana growing operations away from animals and people messing up with it. 

We're trying to find a space enough to grow 4-6 plants, moderately sized plants, you will be looking at 15 - 20 square foot. 

Growing at home and using walk-in closets, garage, basements, or wardrobes tend to make the best practices. You can also purchase a grow tent, or build your own, check the video below. I personally would suggest a grow tent inside a walk-in closet, if you have one.

Avoid rooms on the upper floors, the sun may put a lot of heat and it can cause issues with heat control.

Light-proof grow room is one of the key characteristics for your Grow Room to prevent light leakage and help you to control the environment inside your grow room. 

Other things to consider, the place has to be clean (otherwise, you will put the plants at risk for disease, mold and fungus), away from pets and any type of animals or insects, and comfortably walking into and work in. 

    4. Ventilation for Your Grow Room

    You need make sure there is good airflow. Marijuana requires a well-ventilated space to prevent mustiness and molds. Ventilation also minimize the heat and assists with humidity control; it lowers the environmental stress on the marijuana plant, as well as the chances of pathogenic infection.

    Most of small scale growers put a fan inside the Grow Room, it will cool the space down and move the air around.  

    One important note to pay close attention to; it depends on your setup, you will need to find away to circulate and freshen the air and get rid of the hot air and the extra humidity in side the grow room. Some people cut a hole in the closet, others just leave the grow room's door slightly open, either way, you want to make sure to block the bulk of the opening with something, like Panda Paper, to prevent light leakage and keep a controlled climate. Ducting and carbon filters can also be good solution to minimize scent and control the airflow.

    5. Preparing The Grow Room Walls

    To have a controlled environment and take full advantage of the lights and the energy you use to run your grow room, it's advised to put reflective material up and around the inside walls of your grow room. Mirrors can be an option, but I would go with reflective bubble insulation

    The key take away from this step; you want to make sure that the lights are concentrate on your crops and have been used as efficiently as possible; the reflective wall material surrounds your plants will guarantee that and avoid waste.

    6. Putting Up Your Grow Room Lights

    There are multiple different kind of lights that most growers would rather use:

    • LED
    • Fluorescent
    • High-pressure sodium (HPS)

    Some of the high-end LED lights and HPS systems include built-in fans, would be nice to look into those.

    Fluorescent and HPS tend to the hottest, comparing to LED, so if you end up using them, you may want to pay a closer attention to the temperature inside the grow room, and adding extra fan(s) will be crucial . 

    For small scale hobby growers; Compact fluorescent lights, such as T-5s or CFLs, is the way to go. For the following reasons: 

    1. Compact fluorescent lights are cheaper to set up. Furthermore,reflector, ballast, and bulbs are included in every package. 
    2. Energy efficient and they offer the perfect light spectrum for your marijuana plants.
    3. They release very little heat, and due to that, they can be placed as low as you want them to the plant, which will help to penetrate larger area of your plants, and efficiently get the light to shade the lower parts of your marijuana plants.

    Note that fluorescent lights generate about 25-30% less light per watt of electricity used, which makes it less efficient comparing to the other methods, but again, for a small scale grower, the "efficiency" won't be an issue. If you eventually want to mass produce and start a larger marijuana grow operations, efficiency will definitely matter on your expenses and your bud quality and you will have to look into the other methods. 

    When installing the lights, there are couple of things you need to consider:

    • Make sure the electric parts (for the lights, fans or any electrical equipment/devices you're using) are securely connected and protected from damage. Remember, you will have to water your plants frequently, and it's a hazardous to have uncovered, unprotected and unsecured electrical cabling around. 
    • Better to hang the lights with adjustable chains; as your marijuana plants grow, you will need to adjust the lights upward.
    • Lights should be kept at least one foot below the ceiling.
    • Depending on the wattage, lights should be kept between 8 and 31 inches away from plants. Lights around 150 watts can be kept around 8 inches away from the plant, however, lights as high as 1000 watts should be kept at least 31 inches away from top of the plant.
    • Maximizing your light. Indoor marijuana growing rooms require a minimum 33 watts per square foot.

    7. climate management

    There are three more important environmental factors you need to consider when you're managing your grow room; temperature, humidity, and CO2. Here are few climate manager tools you can use: 

    • Humidifiers
    • Dehumidifiers
    • Humidistat
    • Thermometers
    • Fans
    • CO2 drips/CO2 generators

    Temperature and humidity will vary significantly depending on the climate in your region. 

    It would be a good idea, after finalizing the grow room, to test out the climate inside your grow room for at least couple of days, the temperature, humidity level and lights before you put your cannabis plants and start growing, and adjust accordingly. Lights are too hot, you can add a fan. Adding fan however may cause dryness, and in that case you will need a humidifier. Trial and error till you get the optimal combination of lights, temperature and humidity. 

    At first, preferably, your temperature should range between 65 and 80°F (18 to 26°C). But as you start growing, each growing stage may need different temperature and humidity level

    8. Wire Greenhouse Bench And Place in Your Cannabis Plants

    After you're done with adjusting the climate inside the grow room, it's time to settle your plans down. It's recommended to keeping your marijuana plants up and off the ground just a little bit. It's important to provide some airflow underneath and around the plants.  Racks will also keep the grow room organized, easier to clean possible spills and litter and to move your plants around once they're ready to harvest. 

    As we will be growing in soil, it's better to have a collection of racks cover the grow room's ground. A collection rack can be as simple as a wire Greenhouse bench where your marijuana plants can sit on.

    As for your pots where you will put your soil and plant your marijuana seeds, in general, they should be kept at least 3 to 4 inches apart at the base.


    Final Consideration

    Once you're done with your first harvest, right before you start a new growing cycle, it's recommend to deep clean and disinfect the whole grow room with a strong cleaning agent, to avoid infecting your new crops with any undiscovered bacteria or parasites.

    Step Two: Germinating Your Marijuana Seeds



    Ayad Maher is a Cannabis Industry Entrepreneur, Blogger & Activist. eCommerce Specialist and Owner of a 420 Life Style Company; Monroe Blvd and 421Store.

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