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Do Cannabis Plants Need Carbon Dioxide at Night?

Cannabis grow facilities, especially indoor grow rooms, take advantage of carbon dioxide to bring many useful benefits to each plant’s health and growth. Because the gas can increase your plant’s life and overall performance, you would probably think that feeding your plants this gas 24 hours a day would be a fantastic idea. You may want to hold off on that idea. Before you consider feeding your plants CO2 all day, including night, it’s important to understand what your plants are doing throughout their daily life cycle, as it will help us determine if and when a nightly dose of CO2 for your plants is OK or not.

What Happens During the Day?

When human beings and other mammals breathe, they naturally inhale oxygen and exhale carbon dioxide. Plants do the opposite, taking in carbon dioxide and release oxygen instead. At the same time, they absorb sunlight. This is possible thanks to photosynthesis. This is a process where plants take in sunlight and CO2 in order to convert them into chemical energy. This in turn allows them to create carbohydrates release oxygen into the air. Without this process, no one would be able to breathe.

A second process actually takes place during photosynthesis: respiration. This is the process of plants taking oxygen and carbohydrates to create energy that allows them to grow and release carbon dioxide. The carbohydrates are created through photosynthesis while the oxygen is taken from the atmosphere. Yes, plants do “inhale” oxygen instead of release it during this process. This makes respiration a reverse version of photosynthesis, where plants breathe like humans. CO2 release and oxygen absorption take place. Respiration is actually done 24/7. Photosynthesis, on the other hand, is typically done during the day, not at night.

Can CO2 Do Anything Without Photosynthesis?

As soon as night approaches, all plants go through a period of “rest” where they stop photosynthesizing in order to put all of their focus on respiration. Cannabis plants will naturally stop performing photosynthesis, and no matter what, they won’t take in any carbon dioxide until the morning. Even when you provide grow lights for them, they will still rest when the sun sets and won’t take in the lights. Carbon dioxide can’t do anything for plants without light, so attempting to force-photosynthesize your plants would be a waste of time.

Having your CO2 enrichment system and grow lights stay on while your plants are asleep won’t do anything for them. It will only be a waste of gas and power, so it will be a good idea to turn them off altogether. Just one little tip though: you may want to consider turning your lights and CO2 system on about 20-30 minutes before daylight approaches so that your plants get a head start photosynthesizing when they wake up. But as long as it is midnight, it’s recommended you leave them off. Let your plants rest. Let them respire, and they will grow overnight.

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