cannabis grow room set up with lighting, irrigation, and fans

How to Properly Setup Your Indoor Grow Room Ventilation System

Growing cannabis indoors is an enjoyable and rewarding hobby. Cannabis growers understand how crucial it is to provide their plants with the most suitable conditions for their proper growth and development. Besides investing in quality seeds, nutrients, soil, and lights, you must consider the proper grow room ventilation system.

Ventilation involves exchanging the air within your grow area with fresh air from another room or outside. It helps regulate the temperature, carbon dioxide levels, and humidity and prevents pests and molds in your growing space.

Let’s explore in this blog post how the ventilation system for grow room affects your plants, the importance of proper grow room air circulation, what a grow room ventilation design entails, and other considerable factors for your grow room ventilation system. The article also covers some helpful tips to help with your grow room ventilation plans. You need to do this right to achieve a successful hydroponics growth system.

How Does a Ventilation System Affect Plants?

All farmers know that plants require fresh air to carry out photosynthesis. The process involves changing light energy to chemical energy. It also needs water from the soil and CO2 from the air to produce oxygen and sugars. These sugars are the plant’s primary energy source, emitting oxygen as a by-product. A proper grow room ventilation system will ensure that your plants get sufficient CO2 for photosynthesis and remove the excess oxygen from the growing area.

Grow room ventilation systems also help maintain your plants’ optimal humidity and temperature. Humidity and temperature affect the rate of respiration, transpiration, photosynthesis, and other plant metabolic mechanisms. Respiration involves breaking down sugars into helpful energy and releasing water and carbon dioxide. Transpiration involves water loss from leaves via tiny pores (stomata). A good grow room ventilation design will ensure the humidity and temperature remain within the appropriate range for your plants by eliminating excess moisture and heat from the growing environment.

Ventilation also prevents pests and mold from infesting your plants. Since pests and mildew thrive in humid and stagnant environments, this can destroy your plants and lessen your yield. The best ventilation for a marijuana grow room allows air movement and decreases humidity, which inhibits pest infestation and mold growth.

Why Indoor Grow Rooms Need Proper Air Circulation

Plants grown outdoors usually gain the mitigating effects of precipitation, evaporation, sunshine, and light breezes. Indoor farmers substitute watering systems for precipitation, grow lights for sunshine, and fans for evaporation and breezes. However, some farmers must remember that air usually circulates more naturally outdoors than in your grow environment. You’ll need an air extraction system and a fan to maintain fresh air in your grow room. Here are several reasons:

Control CO2

It’s a primary advantage of a proper grow room ventilation system. Ventilation for grow room generally involves simulating the best outdoor conditions within four walls. It also entails maintaining the ideal CO2 levels for plants. Plants in a closed system will soon exhaust carbon dioxide as they keep breathing it for photosynthesis. That means you require an uninterrupted supply of clean air from another room or the outside. It will help enhance your plants’ growth and yield, irrespective of their type/ species.

Humidity Management

Humidity is another crucial factor that causes challenges with indoor growing systems. Picture the situation inside such an environment with no air circulation. The plants release water vapor all day, increasing your grow room’s humidity. Unregulated humidity attracts many insects and unwanted pests. It may also harm the plants’ overall health.

An effective ventilation system removes the excess moisture and heat in the air. It’s also worth noting that dry air draws water from the plant’s upper parts. As such, the plant absorbs more water from its roots. It also receives more nutrition from the hydroponics system. Ultimately, this leads to slightly improved growth.

Remove Excess Heat

Temperature variations play a massive role in crops. Even the slightest change in degrees can significantly affect your harvest’s quality and quantity. The sun is the primary heat source outdoors. The winds also provide a cooling effect. But this differs in an indoor grow room. Farmers replicate the sunlight with glow lights.

However, these lights may vary. Some may emit much heat, and you can’t regulate heat levels with stagnant, still air. That’s where a steadily circulating air system comes in. It will eradicate excess heat from your grow room.

Prevent Pests & Diseases

Stagnant, humid air will adversely affect every surface in your growing space. Your soilless medium, or topsoil, is particularly susceptible. The medium will maintain dampness and humidity in still air. It can attract mold, mildew, fungi, and some insect species. Pest populations may have slow growth and reproduction because of dry soil. It would be best to have a constant supply of dry air to maintain a healthy dryness level in the topsoil.

Stagnant air also allows flying pests such as gnats to access anywhere freely. You can control these insect activities further by having fans maintain a breeze within the room.

Control Wind Stress & Strengthen Plant Stems

We usually need regular exercises and resistance training to strengthen our muscles as humans. Plants that grow and develop outdoors need something similar to strengthen their stems. Most plants gain strong stems through the constant swaying in the winds. It means they can bear many seeds or fruits later on.

Crops grown indoors in enclosed air don’t have this strength. Instead, they’re like atrophied or weak muscles: fragile and incapable of bearing any weight. Knowing how to set up grow room ventilation is integral if you want your crops to grow upwards and sustain their weight.

Designing a Ventilation System for an Indoor Grow Room

You may have numerous grow room ventilation ideas you want to try out. However, having the right grow room ventilation design is essential.

Designing an indoor grow room ventilation system entails measuring the size and number of filters, fans, ducts, and other necessary components to achieve sufficient airflow in your grow area. Basic ventilation for grow room setup includes several features like:

  • Intake fan. There are different grow room ventilation fans. An intake fan supplies fresh air from another room or outside. Place the intake fan near the floor to provide cool, fresh air for the crops.
  • Exhaust fan. An exhaust fan is another considerable grow room fans ventilation. It carries away stale air from the grow room to another room or outside. Place the exhaust fan near your grow room’s ceiling to blow hot air away from your lights.
  • Carbon filter. It’s a device that applies an activated carbon filter to eradicate odors from the air. You should attach the carbon filter to your ducting or exhaust fan to prevent odor issues. 
  • Ducting. It’s a rigid or flexible tube that joins your fans to another room or outside. Ensure the ducting is short and straight to reduce noise and airflow resistance. 
  • Other components. You may need additional features in your ventilation systems, such as thermometers, speed controllers, timers, silencers, flanges, and hygrometers. 

Step-By-Step Design Guide: How to make a ventilation system for a grow room:

  1. Measure your grow room’s volume in cubic feet (ft3). Do this by multiplying your grow room’s length, width, and height. For instance, if your grow room is 20 feet long, 10 feet wide, and 10 feet high, the volume is 20 x 10 x 10 = 2,000 ft3.
  2. Identify your grow room’s optimal air exchange rate. It’s the number of times every hour that you replace your grow room’s air with fresh air. So, how often should air be exchanged in grow room? The ideal air exchange rate will depend on the grow room’s size, stage, strain of plants, and temperature and humidity levels.
  3. Calculate your grow room’s desired airflow rate in cubic feet per minute (CFM). Do this by multiplying the room’s volume by the required air exchange rate. Once you get your result, divide it by 60 to get your ideal airflow rate. Let’s assume your room’s volume is 2,000 ft3, and you’re aiming for 30 times per hour air exchange rate; your answer would be 2,000 x 30 / 60 = 1,000 CFM.
  4. Your exhaust fan should deliver the expected airflow rate. So, double-check your fan’s specifications to determine its airflow rate. Other factors include the fan’s power consumption, noise level, warranty, and durability. Farmers with large grow rooms will need many fans.
  5. Your intake fan should provide 80% of your exhaust fan’s airflow rate. So, look out for this since it will allow a slight negative pressure in your growing area. It will also enhance airflow efficiency and inhibit odor leakage. Use a passive vent or a smaller fan for your intake fan, provided it doesn’t over-restrict the airflow.
  6. Select ducting that matches your fans’ diameter and has adequate length to reach another room or outside. The ducting should also be light-proof, fire-resistant, and insulated to prevent light leaks, fire hazards, and heat loss. You may also need connectors, clamps, or duct tape to secure your ducting to the vents and fans.
  7. Pick a carbon filter that will handle your exhaust fan’s airflow rate with sufficient capacity for more than one grow cycle. Besides being compatible with your ducting, your carbon filter should have a pre-filter to prevent debris and dust from clogging. Apart from when it gets saturated with odors, try replacing your carbon filter after several months.
  8. Install your grow room ventilation system according to the manufacturer’s guidelines and safety precautions. Place the exhaust fan near your grow room’s ceiling and join it with the carbon filter and ducting. Place your intake fan near your grow room’s floor and connect it to the vent or ducting. You should also install thermometers, speed controllers, timers, silencers, flanges, and hygrometers as required.

Additional Factors to Consider for Your Grow Room Ventilation System

Designing a proper indoor grow room ventilation system is essential. However, other factors may impact your ventilation’s overall performance and efficiency. So, consider the following before setting up grow room ventilation.

Grow Lights

As your grow room’s primary heat source, grow lights can increase the temperature and reduce the humidity levels. Your grow lights should suit the plant size, strain, and stage. It should also be compatible with your ventilation system and grow room size. Only adjust your grow lights’ height and intensity depending on your plants’ needs.

Here are several types of grow lights:

  • Fluorescent lights. These are low-intensity lights that radiate less heat than other lights. Farmers often use these for small plants, clones, or seedlings requiring minimal light intensity. Since these lights are energy-efficient and durable, they’re an excellent option for cheap ventilation grow room or closet grow room ventilation setup. 
  • High-intensity discharge (HID) lights. These are high-intensity lights that generally emit more heat than other lights. HID lights are ideal for flowering and vegetative plants requiring high light intensity. Since they possess a high penetration power, they can cover a relatively large room with bright light. Unfortunately, they typically have a shorter lifespan and consume more electricity than other lights. Farmers also need a cooling system, a reflector, and a ballast to operate them correctly. 
  • Light-emitting diode (LED) lights. They’re medium-intensity lights that emit more heat than fluorescent lights but less than HID lights. Besides being suitable for all plant growth stages, you can customize them to provide various light spectra for diverse plant needs. They’re also energy-efficient and durable, making them an excellent option for your LED grow room ventilation. However, they might have a different light distribution and are costlier than other lights.
  • Ceramic metal halide (CMH) lights. They’re high-intensity lights that emit a full-spectrum light that imitates natural sunlight. They’re suitable for all plant growth stages and can provide admirable buds with enhanced aromas and flavors. They’re also energy-efficient and durable. However, they’re costlier than other lights and need a cooling system and a ballast to operate correctly. 

Air Circulation

The process involves creating air movement inside your grow area to uniformly distribute oxygen, CO2, temperature, and humidity among your crops. You can ensure air circulation by using ceiling, wall-mounted, clip-on, and oscillating fans. So, how much air circulation for grow room? It would help to target an air exchange rate of about 3-5 times per minute in grow room setup ventilation. The process involves adequate air circulation by using fans.

Air circulation will improve your plants’ health and growth by providing clean air, sufficient oxygen and CO2 levels, optimal humidity and temperature, and reduced pest and mold risks. It may also prevent leaf burn, heat stress, reduced growth, and nutrient lockout in your plants.

CO2 Supplementation

The process involves adding more CO2 to your grow area. You can practice CO2 supplementation by using CO2 generators, controllers, timers, or regulators. CO2 supplementation can enhance your plant’s photosynthesis, development rate, yield, and quality. It can also strengthen your plants’ resistance to pests and heat stress. CO2 supplementation increases your grow room’s light intensity and temperature without destroying crops. The process demands thorough planning and monitoring since it can affect your grow room’s humidity, temperature, and ventilation requirements.

Air Purification

It’s the process of eradicating contaminants from the air within your grow room. Your cannabis grow room ventilation can purify air using air filters, ozone generators, ionizers, or other air purifiers. The process can improve your plants’ overall health and quality by providing fresh air, free of pollen, dust, bacteria, viruses, mold spores, and other harmful particles. Air circulation can also improve your health and comfort by reducing headaches, asthma, allergies, and other respiratory complications from poor air quality.


Proper indoor grow room ventilation is integral if you want your cannabis growing hobby to be successful. A reliable ventilation system will provide clean air, CO2 supplementation, optimal humidity and temperature, air purification, and odor control for your plants. Designing a ventilation system for your indoor grow room requires you to calculate the ideal airflow rate, pick the right fans, filters, ducts, and other parts, and install them properly in your grow area. You’ll also need to consider the impacts of air circulation, grow lights, and other factors on your system performance and efficiency.

If you’re looking for an affordable and reliable modular indoor grow room solution, check out Box4Grow. Regardless of whether you’re an independent farmer, collective, or dispensary, we got you! Our Box4Grow grow rooms – greenhouses, drying/ curing, modular, and container – will improve the quality and yield of your marijuana crop or leafy greens. Contact us at (646)612-7734 to learn more about indoor grow room design.




Leave a Reply