How to Build a Grow Room in 3 Easy Steps

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by Morgan

Last update:

August 29, 2023

How To Choose The Right Lighting For Your Marijuana Grow Room

Have you recently bought marijuana seeds or cannabis clones and now want to know how to build a grow room? Not sure where to begin? Don’t worry, you’ve come to the right place. Here’s everything you need to know about building a cannabis grow room indoors.

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Grow Room in a Basement

Setting up your grow room in the basement might just be the perfect plan. Why?

  • Basements are isolated. They’ll provide you with the much-needed discretion.
  • They are usually colder than the rest of the house, which is why they can be your best shot at solving the heating problem.
  • They are extra-secure.

That being said, be careful of mold! Most basements in some parts of the United States are dark and moist, leading to mold on your weed. Make sure to do a good job of buying fans, filters, and have setup excellent ventilation.

Grow Room in a Shed

A detached shed or a similar building is another good option. These might be less discreet than a basement or a room inside your house, but have several compelling benefits.

The only problem with the shed is sharp fluctuations in temperature. On top of insulating the shed well, you might also need to install humidifiers, air conditioners, heater, lights, and fans to provide your cannabis with the necessary environment.

Grow Room in a Garage

People usually have an attached garage with their house, which is a good place for a grow room. Don’t forget to check if your garage has the necessary plumbing and electrical wiring to support a grow room.

Tip: You can use a grow tent inside your garage.

Grow Room in Your Closet

If you are out of options, you can also use an empty closet. But making it work will not be easy. You’ll have to carefully plan the setup. Some of the problems that you can face are:

  • Lack of ventilation, which can lead to heat buildup
  • Difficulty in tending to your plants
  • Limited space
  • Difficulty in light-proofing the closet

Step 1: Essential resources to consider

Growing your own cannabis at home doesn’t require much space. To grow enough cannabis that can last from one harvest to another you’ll only need about a square meter of empty space, which is easily accessible.

You can use a spare room as a grow room, an unused closet or even use your garage if you have one. Once you’ve chosen your space, you’ll want to build out a grow tent, using a grow tent kit, in order to trap the light. There are a number of other factors to consider, which I list below:

Power supply

You’ll need lights and fans to grow cannabis indoors. So make sure that you choose a space that has easy access to electricity. Also make sure you buy the best indoor grow lights you can, like the Mars Hydro TSW 2000w , Bestva 2000w LED Grow Light, or Spider Farmer 4000, because light is the number one contributor to increased yields when growing marijuana.

Water source

Just like every plant, cannabis needs water to thrive. Having a clean and filtered water source nearby is a must. You could even go the extra step by installing a DWC water system to ensure your weed is getting all the nutrients it needs.


Keep in mind that fans and pumps will create some noise. You might want to pick a place that is somewhat isolated. Or else you’ll lose your sleep.  

Flooring type

The most important thing when looking for an area to build a grow room is the flooring type. Carpets and bare concrete are a BIG NO! Both can absorb moisture and other chemicals, which may get released later to ruin your plants.

Step 2: Disinfect the space for plantation.

This is important to prevent fungi or insect infestations, which can damage your precious lot within a matter of days.

Step 3: Set up your grow room.

To get the best yield, it is essential to get the following things right.

Air flow

Your plants consume carbon dioxide and release moisture, and your lights release heat. You’ll have to replace this air with fresh and carbon dioxide-rich air.

Now if the space you’re selecting for your grow room is naturally ventilated, then you can simply install a pedestal fan to keep the fresh air circulating. Good air circulation will make your plants strong, and you’ll have a better yield.

However, if the space you’ve selected is stuffy, then you’ll have to install extractors and intake to ensure adequate circulation.

Carbon extractor filters will extract the carbon dioxide-depleted air. You might want to install a carbon filter to reduce the stink from the air that exits. Also, to minimize the noise and vibrations from these fans you can install them inside a soundproof box or casing.

Inlet fans will intake fresh breeze for your plants. They work best when installed on the lowest area of the wall and on the opposite end of the extractor fans. Use some cushioning to stop the vibrations from travelling through walls and the floor.


Anyone with a basic knowledge of plants would know that light for plants is as important as air is for humans. The rule is simple. If you want the best yield, invest in the best lighting system! Lighting systems are made up of three main parts: ballast, lamp, and reflector.

The problem with lighting systems is the heat they generate. To avoid this problem, you can go for good quality LED grow lights as your main lamps and can supplement them with LED bars. Initially, this setup will cost you more than fluorescent bulbs BUT you will eliminate the heating problem altogether. You could even go with the newest technology and get a quantum board LED lighting system, which is a large circuit board of lights that provide full spectrum lighting.

Also, setting up the right reflecting system is as important as getting the right lighting system.  A good reflecting system will redirect and focus all the generated light onto the plants, ensuring a good yield.

Light Proofing

Your grow room must be lightproof. There are two main reasons for it.

First, grow lights are extremely bright and any light leakage from the grow room can be annoying for you and your family (or neighbors).

Second, light leakage into the grow room can hinder the performance of your plants. You’ll want to use a PAR light meter to know how much light your grow lamps are providing to your marijuana plants. Furthermore, when it’s the night part of the cycle, any light leakage into the room would adversely affect the flowering process and result in a poor yield.


In addition to being light-proof, your room should also be airtight. Why? Because the sweet aroma of cannabis plants is very intense and if your grow room isn’t airtight this smell can grab people’s attention from the outside. Sometimes, the smell may even reach the end of your street.

Plus, if you are planning to get a temperature control system, then a firmly sealed room is a must. Humidifiers and other climate control gadgets will only work if the room is well-sealed.

Oh, and rats <img role=” />. Sealed grow rooms do a very good job of keeping rats (and other pests) from spoiling your hard work.


As mentioned earlier, your flooring shouldn’t be bare concrete or carpet. It should be something that can be easily cleaned and is resistant to humid conditions. Layering your concrete floor with epoxy or paint would do the job. Vinyl flooring is another good option.

Safety precautions

Although not many cannabis growers get into an accident, the risk is always there. They say prevention is better than cure. So make sure all your safety precautions are in place. Here are the most important ones:

  • Always have fresh air circulating in your grow room so that your electrical appliances don’t overheat and catch fire.
  • Always have a fire extinguisher near your grow room so that in case of a fire you can prevent it from spreading and destroying the rest of your property.
  • Make sure your electrical appliances (humidifiers, fans, and lights) don’t get into contact with water.

Now you know how to build a grow room in your home!

And that’s it, folks! Keep these principles in mind, and you’ll set up a killer grow room in no time. Once you set it up, invest in high-quality seeds to grow the best cannabis ever.

Remember, setting up the right grow room is only part of the process. The quality of your seeds, your growing skills, and your cannabis processing methods all play an important role in determining the ultimate quality of your yield.


1. Is it cheaper to build your own grow tent?

Yes, it is cheaper to build your own grow tent. You can save money by making a DIY project out of wood or PVC pipe that you can find at any hardware store. You will have to do some research on what materials are best for the type of plants you want to grow and how much light they require.

2. How do I build a small indoor grow room?

To build a small indoor grow room, you’ll need to purchase some supplies and build some basic structures. First, you’ll need to buy a grow tent, grow light, and a ventilation system. The grow tent will provide you with a space to grow your plants, the grow light will provide the light they need to grow, and the ventilation system will keep the air in the room fresh.

3. How many plants 4X4 grow room?

The number of plants that can grow in a 4×4 grow room is dependent on the size of the plant. For example, small plants like tomatoes and peppers need less space while larger plants like cannabis flowers require more space, so it’s good to know how much space your plant needs beforehand.

4. How do you make a smell-proof grow box?

To make a smell-proof grow box, you would need to seal it up with plastic sheeting that is vapor permeable. You should also ventilate the area by using a carbon filter or an air scrubber.

5. Do I need a grow tent to grow indoors?

You don’t necessarily need a grow tent to grow indoors, but they can be helpful in creating an ideal growing environment. A grow tent helps to control the climate and humidity levels inside, which can be important for cannabis plants. They also help to protect plants from pests and other outside influences.

🌿  Join my "growing" community 
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cannabis farmers! 👩‍🌾

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from seeds to smoke! 
— Morgan, 420GreenThumb 🌱

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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.

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