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Carbon Dioxide and Better Indoor Harvests

Part 3

Are you making the mistake of supplementing with CO2 at night? Don’t. Plants actually need oxygen, not CO2, at night—and they can provide it fine for themselves. Unlike CO2, there’s no need to supplement. Thus far, we’ve talked about the importance of CO2 supplementation for better grow room harvests, but it’s also important NOT to supplement with CO2 sometimes if you want your plants to be healthy and produce high yields.

When? At night, during a process called “respiration,”—and it’s just as important to plant health, growth and yield as photosynthesis is.

What happens during respiration?

During daytime photosynthesis, plants produce sugars and store them for later digestion (with CO2 and water expelled). During nighttime respiration, plants “digest” these stored sugars, and they need oxygen to do that.

It works like this: Plants use oxygen to break down the stored sugars (much as humans and other mammals do) into energy. Plants then use this energy for various metabolic processes needed for growth.

Provide at least 12 hours of complete darkness each day for respiration

Although plants can digest stored sugars during daylight, the energy produced is used much more efficiently at night.

In fact, many plants won’t flower if they’re not given 12 hours of uninterrupted darkness. Introducing even small amounts of light can interrupt respiration.

The flowering cycle

As plants move through the flowering phase, they become more robust. They become bigger and sturdier, some produce more branches with small leaves (making photosynthesis and respiration cycles even more efficient). Of course, bigger plants produce more flowers or buds—and more efficient plants, in turn, produce better quality, higher-yielding harvests.

A final note: Run a dehumidifier

In addition to carbon dioxide, plants also “exhale” water during respiration. Growroom temperatures are lower at night, too, and this can mean condensation on plants and humidity levels that are too high. Run a dehumidifier to maintain optimal humidity levels for all stages of growth.