sourcing co2
Carbon dioxide is a colorless, typically odorless gas made up
of one carbon atom attached to two oxygen atoms. It is an
important aspect of photosynthesis and must be present in
some form for plants to grow, which means a well-run indoor
garden generally benefits from some additional carbon
dioxide, provided the garden has no other issues that must
be corrected first.
Plants absorb carbon dioxide through their stomata,
small openings in the epidermal layer of the undersides of
their leaves. These openings allow CO2 in for use during
photosynthesis and allow the plant to vent out oxygen and
water vapor. During the reaction, plants take in six water and
six carbon dioxide molecules, and light, to form one sugar
and six oxygen molecules. The plant vents off the oxygen,
and uses the sugar for growth. The formula looks like this:
Carbon dioxide (6CO2) + water
(6H2O) in the presence of light
and chlorophyll
= carbohydrate (C6H12O6)
+ oxygen (6O2)
A shortage of
carbon dioxide
hinders or
even prevents
plant growth,
while a moderate
boost allows many
plants to thrive, especially in warmer-than-usual
environments, which are often
the case with indoor gardens.
When supplementing CO2, the goal
is to provide the ideal range of additional CO2, which should be higher than
atmospheric conditions, most commonly in
the range of 1,000-1,300 ppm, depending on the
specific needs of the crops. CO2 levels exceeding this range
have little additional positive effects, and levels exceeding
1,500 ppm may hinder plant growth. Light levels and other
atmospheric conditions also play a role in how much extra
CO2 is ideal for a garden. It’s always best to research the
needs of what you’re growing.
Surrounding the plant’s stomata are guard cells that allow
the stomata to open when light and moisture are conducive
to growth, and to close in times of drought, high heat and
darkness. This is why supplemental CO2 is recommended
only during the lit hours of a garden, whenever possible,
unless the source of supplemental CO2 is continuous and
there is no way to turn it off.
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Maximum Yield USA | April 2015
CO2
“A shortage of carbon dioxide
hinders or even prevents plant
growth, while a moderate boost
allows many plants to thrive.”
Given that CO2 is an essential piece of the photosynthesis puzzle, most indoor gardeners will want to provide
their plants with carbon dioxide in one form or other.
Luckily, there are many options. Here are nine ways to
add CO2 to your growroom.
Fresh Air
Fresh air contains about 400 ppm of CO2, and plants
grown outdoors only receive CO2 from what is available
in this air, which is an adequate amount for normal plant
growth. For indoor growers looking to constantly provide
this amount of CO2 to their gardens, it is as simple as
providing fresh air—continually removing the air that is
depleted of CO2 from inside the garden and replacing it
with fresh air from outside. Fans are used for this purpose,
with higher cfm-rated fans moving more air per minute.
Using this method, a grower can only ever supply atmospheric levels of CO2 to their plants and nothing more, and
run the risk of altering their growing environment in other
ways, such as increased humidity levels.