Although often neglected, good ventilation is an essential aspect of running an efficient and clean grow room. Most cannabis pests and infestations are the result of a ventilation problem. Here's how to properly ventilate your cannabis grow for happy plants and abundant yields!
Ventilation is an extremely important part of indoor growing, but is often neglected. Without proper ventilation, your plants can suffer from growth retardation, disease and pest infestation. This guide will tell you everything you need to know about proper ventilation for your grow room/closet.
Why is ventilation so important when growing cannabis?
- For photosynthesis: plants need fresh air to fuel the process of photosynthesis, in which they convert light, water and carbon dioxide from the atmosphere into food.
- To breathe: plants breathe to convert the glucose and oxygen from photosynthesis into energy that fuels their growth.
Without fresh air, your cannabis plants will literally starve. But before that happens, the lack of fresh air in your grow room creates a breeding ground for pathogens and pests. Without proper ventilation, warm, stale air collects around the plants, creating a warm, humid environment that pests and infestations love.
Understand how to optimise ventilation
Many inexperienced cannabis growers feel a little lost and overwhelmed when it comes to ventilation. However, the basic principles of ventilating a grow room are simple: remove the old, humid air from the room/cupboard and replace it with fresh, oxygen-rich air from outside.
If you are reading this article, you may be wondering what makes the air in a cupboard or a room warm and humid. Let's look at this together :
- Sweating
Cannabis plants naturally sweat (or transpire). This process is important for the plants to transport water and nutrients from the soil to their branches, leaves and flowers. Cannabis plants transpire through the stomata and cuticle of the leaves, but also through the lenticels (pores distributed throughout the plant tissue, including the stems). This process creates a draught that pulls water up from the roots and redistributes it throughout the rest of the plant. The water that your plants sweat out naturally evaporates into the air of your grow room, gradually increasing the relative humidity.
- The heat from grow lamps
All grow lamps give off some form of heat. And although most modern LEDs tend to operate at much lower temperatures than traditional high pressure discharge lamps, many growers still opt for the latest lamp models (metal halide, high pressure sodium or both) as these tend to give better yields. Without good ventilation, your grow lamps will inevitably raise the temperature in your room/cupboard.
The best way to keep your grow room ventilated is to use an exhaust system that draws old, warm air out of the room/cabinet from above and blows fresh, oxygen-rich air in from below to flow through the leaves of your plants. Depending on the size of your room, you can also use simple fans to move the air. Read on to find out more about using extractors and fans.
Essential tools for a better ventilated grow room
Here's a list of all the essential items you need to properly ventilate your grow room.
Air extractors
Exhaust fans pull stale air out of your grow room. Since warm air naturally rises, you should place the extractor at the top of your room/closet. Some grow lights or reflectors already have a connection to which you can attach an exhaust fan.
Remember that there are different models of extractors on the market and you will need to adjust the power of your extractor to the size of your grow room. The power of indoor extractors is usually expressed by the English abbreviation CFM "cubic feet per minute", which is usually converted to "cubic metres per hour" in the European market. Below you will learn how to calculate the CFM you need to properly ventilate a room or grow cabinet.
Understanding the CFM
To calculate the volume of your hobby closet/grow room, multiply its length, width and height (ideally in metres). For example, for a medium sized hobby grow cupboard of 1x1 m, the calculation should look like this:
1 m (length) x 1 m (width) x 2 m (height) = 2 m³.
For a grow tent of this size, we recommend that you choose an extractor with a capacity of at least 280 m³/h. This way, the extractor fan will completely exchange the air in your grow room every minute.
If you find extractors whose output is given in CFM, convert the unit to cubic metres per hour using this handy converter.
Activated carbon filters
Activated carbon filters are designed to remove pollutants from the air. When connected to an exhaust system, they also absorb the terpenes released by your cannabis plants, purifying the air leaving your grow room. Charcoal has a high density (a single gram of activated charcoal has a surface area of 3,000 m²) and therefore activated charcoal filters are very effective in treating odours from a cannabis grow room.
Oscillating fans
Oscillating fans are the final piece of the "ventilation puzzle". Although they may seem harmless and cheap, fans placed in strategic locations can provide effective air circulation around the plants. The breeze will not only strengthen the branches, but also help prevent stagnant air from accumulating around your area, reducing the risk of pests or infestations ruining your crop.
Choose between passive and active air intake.
The air intakes of a crop are essentially the source from which air enters your growing space. Passive air intake relies on the natural flow of air through holes or openings in the walls of your room/cabinet. Active air supply, on the other hand, works by directing air into your grow room with the help of an intake fan. This provides much better air circulation, making it by far the best method of ventilating a grow room. The CFM of the intake fan usually needs to be lower than the CFM of the exhaust fan to ensure negative air pressure in the room.
The importance of negative air pressure
As indoor growers, we are responsible for replicating Mother Nature's conditions and providing the best possible growing environment for our plants. By measuring the air pressure inside a cabinet, we can better control the grow house environment and specifically ensure optimal airflow.
Ideally, the air pressure in the grow room should be negative. This would mean that more air is flowing out of the room than in, making it easier to control temperature, humidity and CO₂ in the grow room, while minimising the smell of your plants (as old air will not accumulate around the cabinet/room).
Check out an air extractor at first price! One click on the link!
Is it better to mount the extractor inside or outside the growing cabinet?
This is a common question among inexperienced growers. Generally, it is recommended to install the extractor and all parts of the exhaust system inside the grow cabinet to minimise noise pollution. However, if you are short on space or cannot cope with the heat inside the grow cabinet, you are welcome to place the exhaust fan outside. Wherever you place it, the most important thing is that your exhaust system is airtight.
How to ventilate a grow cabinet
Most indoor growers choose to cultivate in grow boxes. Fortunately, most modern models already have air intakes or doors prepared to accommodate a ventilation system. Here are the basics for installing an air extraction system in a grow cabinet.
Install the exhaust filter and exhaust fan.
Install your activated carbon filter and then the exhaust fan. We recommend installing both before you position the lamps, as it can be tricky to move a lamp to position the exhaust system.
Installing the grow lamps
After you have installed the filter and the fan perhaps the TT 125 UN, position the lamps by fixing them with pulley hooks.
Connect everything to the air ducts
Once you have installed the lamp, the air filter and the extractor inside the cabinet, connect everything to the air ducts. Remember to use the air duct clamps to hold everything in place and have tape ready to tape over any cracks in the system.
Arrange the air ducts from the cabinet to the outside.
Outside your grow cabinet, lay out air ducts to direct the air from the extractor to a window (or other place where you want to vent the warm air). Keep the path of the air ducts as straight and short as possible to maximise efficiency.
Take advantage of passive and active ventilation to bring fresh air into your system.
If you rely on passive air intake, make sure the air intakes of your grow cabinet are open. Also, keep a window open near your cabinet to replace the warm air that escapes from the grow box.
If you are using active ventilation instead, install a two-speed fan in the air intake of your cabinet.
How to ventilate a micro grow cabinet
Micro growers who grow only one or two plants in a cabinet or chamber can use a very simple ventilation system. In fact, aerating a microculture can be done with almost no money. All one needs to do is open a window near the closet/chamber/wardrobe several times a day and use oscillating fans if necessary to properly ventilate the grow environment. Growers using low wattage LEDs, CFLs or HID systems (250W or less) should not have heat problems. Humidity management can also be very simple in a microculture, possibly with the help of a dehumidifier.
How to ventilate a greenhouse
Greenhouse growers should make sure they have several air inlets that can be opened and closed as needed. Most simple greenhouses covered with a plastic sheet have ventilation flaps that can be opened and closed manually. In the worst case, you can open the doors a little or remove a panel in glass greenhouses.
Letting in a slight breeze can make a big difference. A greenhouse can get very humid, especially if it is filled with leafy and sweaty cannabis plants. Whether indoors or outdoors, as plants mature they exhale more water vapour and increase the relative humidity of the surrounding space. Good air circulation is essential in any growing area. In the last weeks of the flowering period, most serratias with large and compact inflorescences prefer to open all vents. In addition, installing do-it-yourself aeration to provide extra air to the environment can help banish the risk of bud rot.
How do you stay inconspicuous when ventilating a closet or grow room?
We recommend investing in shutters made from willow rods and fixing them in front of the window you are venting from. It will hide what is going on in your grow room while letting the air in. You can then start connecting the air ducts. Many people simply attach a sheet of plaster or plywood to the window frame and drill a hole for the duct to pass through.
Additional products recommended by your Ethnic World team :
Quiet: sound-insulated / EC motor
EC motors are "new generation" motors, usually more power, more pressure, quieter, with electronic switch (EC), they wear out less quickly, we recommend them to you 100%.
KSB 125 - 330 m³/h (insonorisé)
Circular Duct Fan TT Pro 125 EC Un - 450 m³/h (EC, variable, contrôle de la température)
EC Power Box 125 mm 280 m³/h (EC, variable, contrôle de la température)
ISO-MAX 160 - 430 m³/h (Can-Fan) (Insonorisé, variable)
Q-Max EC 160 - 746 m³/h (Can-Fan) (EC Insonorisé, contrôleur externe pour la vitesse)
