co2 in the garden
1,500 ppm are unnecessary. There
is no benefit to providing more CO2
than your plants can consume and
carbon dioxide levels above 2,000
ppm can harm your plants by limiting
transpiration and reducing nutrient
uptake. Carbon dioxide is generally
safe for humans at these levels, but
levels above 6,000 ppm are harmful to
humans after exposure for a period of
time, especially for those with respiratory problems. For this reason, if you
are enriching your garden with CO2,
it is vital that you use a monitor in
conjunction with your enrichment
devices to control the levels at all
times. The generally accepted sweet
spot in the indoor gardening world
is maintaining levels between 1,000
and 1,800 ppm, with most gardeners
agreeing on 1,500 ppm as the level of
maximum benefit. With few exceptions, it is unnecessary to provide the
garden with CO2 enrichment when
the lights are off—this is usually
only necessary when the lights in
the garden are on and photosynthesis is in full swing.
There are several different ways
of delivering CO2 to your garden.
The simplest way to replenish the
CO2 levels is by venting, where a fan
exhausts garden air out and replaces
it with air from the outside. This
replaces any air that has depleted
CO2 levels. This method is common,
but it limits the garden to only the
64
Maximum Yield USA | February 2014
atmospheric normal levels of CO2,
does nothing to enrich the air with
higher levels and it is not without
problems, primarily related to the
other aspects of the garden’s climate.
For example, if it’s humid outside,
you introduce humidity into the
garden, which can lead to fungus
growth on your crop, and since most
gardens are already humid, no more
moisture is needed. Introducing outside air can also introduce pests into
the space. Lastly, if the temperature
outside is hotter than you want your
garden to be, you must compensate
for the introduction of outside air
with your air-conditioning system.
Most gardeners who start
out with a venting
system eventually
move to a different
type of enrichOnce
ment system.
There are also systems available that
boost CO2 levels with decomposing
natural materials. These come in a
package that you place in the garden,
during which time the decomposition off-gasses CO2 into the garden,
boosting the levels somewhat. These
products are natural and inexpensive
and don’t require a CO2 monitor
or other equipment to operate, as
there is little chance of overdosing
your garden unless you are using an
extremely small space. However, CO2
volumes will be variable, and it is difficult to determine exactly what ppms
can be reached. Additionally, they
can’t be turned on and off with your
the CO 2
levels drop
below what
is normally
available in the
atmosphere, plant
growth will
be negatively
affected, often
dramatically.
"