Importance of Proper Ventilation

Many new growers forget the importance of proper ventilation and temperature control. Marijuana plants need not only light but also CO2 to efficiently photosynthesize. This is why providing sufficient ventilation and fresh air into your enclosure is extremely important to the health of your plants.

Marijuana plants thrive in temperatures ranging between 70°F and 83°F (21.1°C – 28.3°C). The most common reason for high temperatures in your enclosure is caused by the heat generated from your grow lights. You must select the proper lighting for the size of your grow space.

I have witnessed, time after time, an excited new grower purchasing lights that are too powerful for their enclosure. This is because too many growers are given incorrect information or do not execute the proper planning.

Having a clear strategic plan to achieve proper ventilation in your grow space is absolutely necessary to have a successful harvest.

Types of Ventilation

Inline Exhaust Fans

Exhaust-FansA common way to control temperature in your grow room is to extract the heat generated by the grow lights with an inline fan. These inline fans come in various sizes, are quite powerful, and can be very quiet at the same time.

A sealed grow enclosure with only 1 intake inlet and 1 exhaust outlet, can be sufficiently ventilated with a single inline fan. These fans are more efficient at pulling air (directing air out of the enclosure) than they are pushing air (forcing air into the enclosure).

By pulling hot air out of the exhaust outlet, you naturally create a vacuum that pulls fresh air into your enclosure through the intake inlet. This gives your plants the much needed CO2.

Some grow light hoods also have built-in ports that easily connects to your inline fan to extract heat directly from the light bulbs. This makes it easier for you to keep your enclosure within the correct temperature range because it does not allow the lights to heat up your entire enclosure.

A great accessory for your inline fans is a Fan Speed Controller. This unit is placed in between your grow light’s power plug and your home’s power outlet. The little device lets you to adjust the speed of your fan, allowing you to fine tune your ventilation.

Oscillating Fans

Air-FansOscillating fans are used to circulate air inside your enclosure. These fans help move warm air away from your marijuana plants, keeping them cooler and helps reduce any heat stress. Preventing stagnant air inside your enclosure is very important and can determine the quality of your harvest.

Circulating air also helps strengthen the plants stems as it grows. Just like in nature, plants encounter winds, storms, and various environmental changes. The plants build up strength and rigidity during these times to minimize any damages it may face.

Circulating fans are inexpensive and come in an assortment of sizes. There is no doubt that you can find a size that fits your grow room.

Air Conditioners

Air-ConditionerUsually used for larger grow operations, an air conditioner unit can help reduce high temperatures. Smaller grows, like in a grow tent or closet, should not need an air conditioner if proper planning was done.

Portable air conditioners are the easiest to use because they can conveniently move from one location to another. Many of these portable air conditioner have built in temperature control settings and timers ensuring your enclosure is at the right temperature at all times.

Although your energy bill may increase with the use of air conditioners, they are a great option if you have trouble keeping your temperatures within range.


DehumidifiersDuring the flowering stage, it is not uncommon to experience higher than normal humidity levels. You will usually see this spike in humidity due to the formation of moist marijuana buds on plants.

There are several way to control this issue and avoid possible growth of mold or other plant diseases.

Using an electric dehumidifier is a simple way to remove moisture from the air. Simply plug it into an outlet and set the desired level of humidity. The dehumidifier will extract the moisture and contain it in a reservoir.

If you are growing in a small space, using dehumidifying crystals can be a more simple and less costly answer to high humidity.

Simply open the container of dehumidifying crystals and place it inside your grow enclosure. The crystals will extract the moisture in the air and retain the water in the crystals itself.

Since the crystals will eventual be full of water, you will occasionally need to dump it out and refill with fresh crystals.

Proper Planning

I cannot stress how important it is to plan out your ventilation strategy. You may not see difficulty in controlling temperatures during the vegetative stage, but do not be left unprepared when it comes time to flower your plants.

The flowering stage is when most growers face temperature issues. Using the tools listed above can help ensure that you have a successful harvest.

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