dioxide levels can increase Cannabis growth speed a great deal, perhaps
even double it. It seems that the plant evolved in primordial
times when natural CO2 levels were many times what they are
today. The plant uses CO2 for photosynthesis to create sugars it
uses to build plant tissues. Elevating the CO2 level will
increase the Cannabis plants ability to manufacture these sugars and
plant growth rate is enhanced considerably.
CO2 can be a pain
to manufacture safely, cheaply, and/or conveniently, and is
expensive to set up if you use a CO2 tank system. CO2 is most
usable for flowering, as this is when the plant is most dense
and has the hardest time circulating air around its leaves. If
your strictly growing vegetatively indoors, (transferring your
plants outdoors to flower), then CO2 will not be a major concern
unless you have a sealed greenhouse, closet or bedroom, and wish
to increase yield and decrease flowering time.
For a medium sized
indoor Cannabis grow garden, one approach is to used CO2 canisters from
wielding supply houses. This is expensive initially, but fairly
inexpensive in the long run. These systems are good only if your
area is not too big or too small.
The basic CO2 tank
system looks like this:
20 lb tank $99
Fill up $15-20
Worst case = $395
for CO2 tank setup synced to a exhaust fan with a thermostat.
CO2 is cheaply
produced by burning Natural Gas. However, heat and Carbon
Monoxide must be vented to the outside air. CO2 can be obtained
by buying or leasing cylinders from local welding supply houses.
If asked, you can say you have an old mig welder at home and
need to patch up the lawnmower (trailer, car, etc.)
For a small
closet, one tank could last 2 months, but it depends on how much
is released, how often the room is vented, hours of light cycle,
room leaks, enrichment levels and dispersion methods. This
method may be overkill for your small closet.
It is generally
viewed as good to have a small constant flow of CO2 over the
plants at all times the lights are on, dispersed directly over
the plants during the time exhaust fans are off.
exist to conserve CO2, but this can cost money. When the light
is off you don not need CO2, so during flowering, you will use
half as much if you have the CO2 solenoid setup to your light
timer. When the fan is on for venting, CO2 is shut off as well.
This may be up to half the time the light is on, so this will
affect the plants exposure times and amount of gas actually
using bottled gas is better, since manufacturing it adds to
greenhouse effect, and bottled CO2 is captured as part of the
manufacturing process of many materials, and then recycled.
Fermenting, CO2 generators, and baking soda and vinegar methods
all generate new CO2 and add to greenhouse effect.
from fermentation and generators is possible. A simple CO2
generator would be a propane heater. This will work well, as
long as the gases can be vented to the grow area, and a fan is
used to keep the hot CO2 (that will rise) circulating and
available below at the plants level. Fire and exhaust venting of
the heat are issues as well. A room that must be vented 50% of
the time to rid the environment of heat from a lamp and heater
will not receive as much CO2 as a room that can be kept unvented
for hours at a time. However, CO2 generators are the only way to
go for large operations.
vinegar over baking soda will work if you don not have many vent
cycles, but if you have enough heat to make constant or regular
venting necessary, these methods become impractical. Just pour
the vinegar on baking soda and close the door, (you lose your
CO2 as soon as the vent comes on). This method leaves a great
deal to be desired, since it is not easy to regulate
automatically, and requires daily attention. It is possible
however, to create CO2 by fermentation, let the wine turn to
vinegar, and pour this on baking soda. It is the most
cost-effective setup for most closet growers, for whom $400 in
CO2 equipment is a bit much to swallow.
yeast is constantly killing itself; it takes a lot of space. You
need a big bin to constantly keep adding water to, so that the
alcohol levels will not rise high enough to kill the yeast.
Sugar is used quickly this way, and a 10 pound sack will run
$3.50 or so and last about 2-3 weeks. This is also difficult to
gauge what is happening as far as amounts actually released. A
tube out the top going into a jar of water will bubble and
demonstrate the amount of CO2 being produced.
bicarbonate mixed with vinegar, 1 tsp: ~30cc- this will gush up
all frothy as it releases CO2. do it just before you close the
door on your plants. A MUCH cheaper way to provide CO2 is 2 Oz
sugar in 2 liters of water in a bottle [sterilized 1st with
bleach and water, then rinsed], plus a few cc urine[!] or if you
insist, yeast nutrient from a home brewing supplier. Add a
brewing yeast, shake up and keep at 25 deg celsius[~70 F] . Over
next 2 weeks or so it will brew up about 1/2 Oz CO2 for every Oz
sugar used. Keep a few going at once, starting a new one every 3
days or so. With added CO2 growth is phenomenal!!! I personally
measured 38cm growth in 8 days under a 250watt HPS bulb[tubular
clear, Horizontal mount.
A good container
is a 1 gallon plastic milk jug, with a pin-hole in the cap.
Also, the air-lock from a piece of clear tube running into a jar
filled with water will keep microbes out and demonstrate the
fermentation is working.
A variation is to
spray seltzer water on the Cannabis plants twice a day. This is not
recommended by some authorities, and receives great raves by
people who seem to feel it has enhanced their crop. It stands to
reason this would work for only a small unvented closet, but may
be right for some situations. It could get expensive with a lot
of plants to spray. Use seltzer, not club soda, since it
contains less sodium that could clog the plants stomata. Wash
your plants with straight water after 2 or 3 seltzer sprays. It
is a lot of work, and you can not automate it, but maybe that is
good! Remember, being with the plants is a beautiful experience,
and brings you closer to your spiritual self and the earth.
Seltzer is available at most grocery stores. Club soda will work
if seltzer water is not available; but it has twice as much
sodium in it. A very diluted solution of Miracle Grow can be
sprayed on the plant at the same time. One factor of using
selzter water is it raises humidity levels. Make sure your
venting humidity during the dark cycle, or you could risk fungus
and increased internode length.
CAUTION: Don not
spray too close to a hot bulb! Spray downward only, or turn off
the lamp first.
Even though CO2
enrichment can mean 30-100% yield increases, the hassle,
expense, space, danger, and time involved can make constant or
near constant venting a desirable alternative to enrichment. As
long as the plant has the opportunity to take in new CO2 at all
times, from air that is over 200 ppm CO2, the plants will have
the required nutrients for photosynthesis. Most closets will
need new CO2 coming in every two or three hours, minimum. Most
citys will have high concentrations of CO2 in the air, and some
growers find CO2 injection unnecessary in these circumstances.
Cannabis growers have
reported to High Times that high CO2 levels in the grow room
near harvest time lower potency. It may be a good idea to turn
off CO2 2 weeks before cannabis harvesting.