INDOOR
ENVIRONMENTAL CONTROL
BY NOW YOU HAVE THE KNOWLEDGE YOU NEED to set up the basic environment
for your indoor plant. As the grower, you have total control over that
environment and you need to make sure it meets all of your plant's needs.
This chapter deals with controlling four important environmental factors
for plant growth: nutrients, soil, water and air. The most important environmental
factor, lighting, was covered in detail in Chapter 5. With the right amount
of care in all five areas, your plants with thrive.
NUTRIENT CONTROL
Remember nitrogen, phosphorus and potassium (NPIO? These macronutrients
are the primary ingredients needed in soil to ensure a healthy marijuana
crop. In addition, the secondary supplements Ca (calcium); Mg (magnesium);
and S (sulfur), or CaMgS for short can be used to promote plant growth
and health, and are also part of the macronutrient group. Secondary supplements
are generally found in soil, but not always in sufficient amounts. There
are eight additional plant micronutrients: iron (Fe), Boron (b), chlorine
(CD, manganese (Mn), copper (Cu), zinc (Zn), cobalt (Co) and molybdenum
(Mo). These eight micronutrients are less important for good plant health,
than are NPK and CaMgS. Check your soil bag to see if it contains micronutrients.
The nutrients and nutrient levels in your soil can be monitored using
either electronic or manual nutrient testers. Most growers however do
not have the luxury of such expensive items and have to control everything
by hand, using judgement. Don't despair! Growers the world over have successfully
tended to plants long before the invention of electronic readers. The
key to nutrient control is to plan your feeding in advance of growing
your plant. This way, everything else you feed to your plants is simply
a supplement to the plan. You can always adjust your plan for future grows
of the same strain based on what you learn the first time around. Remember
though that each strain is different and will probably require changes
to the following basic routine.
1. For seedlings, use a soil with an even NPK ratio, such as 10:10:10
or 5:5:5. No nutrients should be added, but if you do find that need to,
add them in very small doses (no more than l/8th of the strength of what
it says on the bottle).
2. After germination do not feed for three weeks, unless seedlings show
signs of yellowing. In either case, feed them a dose of NPK with an even
ratio (10:10:10) or a higher N than P and K ratio (20:10:10) at 1/4 of
what is recommended on the label for the first week and continue this
once a week until calyx (pre-flowers) show on the plant.
3. If your plant shows any yellowing, increase the feeding strengths until
yellowing stops. Increase in small steps from 25 to 33 percent before
trying 50 percent or higher. If plant health does not improve, consult
chapter 13 on problem solving a nutrient deficiency.
4. In the second week of growth you should be adding secondary nutrients
to your plants. Mix secondary nutrients at 1/4 strength of what it says
on the bottle. Continue adding secondary nutrients once every other week.
5. Once every 2nd week add micronutrients at 1/4 strength of what it
says on the bottle.
6. As soon as calyx development shows, switch to a food with a higher
P than N and K ratio (10:20:10). Continue to feed your plants as usual,
exchanging the older vegetative food for this new flowering food.
Remember that cannabis burns easily and does not need full strength nutrients.
It is better to increase the frequency of your feeding rather than the
strength of your foods if you discover that your plant needs more food.This
may be more time consuming, but it reduces the risk of plant burn immensely.
Some plants require more foods in higher doses than others do. The frequency
of your feeding and food strengths will vary from strain to strain; however
the basic elements of these foods and their composition will not. Your
plants need NPK as the basic building blocks of their diet. You need to
know how to select for these in soil and you need to know how to keep
them in your soil type. Some soils also diminish in nutrients more quickly
than others do because of the soil's composition and its nutrient- and
water-retaining qualities. Whenever you select a soil type for cannabis
try to find one that has an even NPK balance like a 10:10:10. It is easier
to maintain this balance if you use a balanced NPK vegetative growth feed.
If your soil is higher in P or K then it is hard to balance it using other
foods.
FOR EXAMPLE:
A soil type of 10:20:10 needs to be balanced back to 10:10:10 or else
the high levels of P will cause the plant problems accessing the other
N and K nutrients that it also needs for vegetative growth (also a condition
known as 'Nutrient Lockout'}. In order to balance it back you need to
wait until the next time you feed and only add 10:0:10 to the soil. This
is because you would expect the remaining nutrients in the soil to be
already high in levels of P. The hard part is finding a. bottle of nutrients
that have 10:0:10 on the label. So in order to avoid this problem we select
a balanced soil in the first place.
Growers mainly have four types of nutrients at their disposal: vegetative
primary nutrients, flowering primary nutrients, secondary nutrients and
micronutrients.The list below contains classic examples of food types
that you may find or work with.
1. N10:P10:K10-This is an example of a balanced vegetative primary nutrient
pack.
2. N10:P20:K10 -This is an example of a flowering primary nutrient pack.
3. NQ:P20:K10-Tnis is an example of a flowering food without N.
4. N10:PO:K10-This is an example of a vegetative food without P.
5. N10:P20:K20-This is an example of a flowering food that is not suitable
for cannabis because of its equal P and K values but lower N values.
6. al:Mgl:Sl -This is an example of a balanced secondary food.
7. Ca2:Mg3:S4 -This is an example of a secondary food.
8. N10:P10:K10:Cal:Mgl:Sl-This is an example of bottle of food that contains
both primary and secondary nutrients.
9. N10:PO:KO -This is a pure N supplement.
10. NO:P10:KO -This is a pure P supplement.
Micronutrients are sometimes listed in ratios like NPK values but it is
more common to just find micronutrients measurements. One good brand of
micronutrient that is used by nearly every grower is called Formulex®.
Growers ensure that at least some secondary nutrients are added to the
soil mix or in with feeding routine because some secondary problems are
hard to find. Ca problems are awkward to detect because a Ca deficiency
only stunts growth and does not appear to display anything else usually
associated with a nutrient disorders like: leaf discoloring, rusting,
blotching, leaf curling or any other chlorot-ic condition that one would
expect.To solve problems like this, growers always try to prevent instead
of cure. Ensure that your soil or feeding routine has some sort of secondary
nutrient plan incorporated into them.
Professional growers get their supplements in separate packs of N, P and
K.That way they have total control over their primary macronutrients.
Using these separate packs, they can mix vegetative foods, flowerings
foods, pure l\l, pure P and pure K supplements — whatever they want
and in whatever strengths they want - 20:10:10, 20:5:5, 5:20:5, etc.
Problematic Nutrients
Recalling that some strains may require more of a certain nutrient than
others, we know that a balanced food might not have enough of that nutrient
to allow the plant to grow without expressing a nutrient disorder. You
may have to first identify the strain's 'problematic nutrient(s)' before
finding a suitable feeding product. Mg is a common problematic nutrient,
which means that many strains are more likely to experience a Mg nutrient
disorder. In order to correct this you would have to use either pure Mg,
a secondary nutrient feeding product or preferably a secondary nutrient
product with higher Mg to Ca and S ratios.
Problematic nutrients are on the increase with stabilized plant breeding.
As breeders develop strains for certain characteristics — flowering
times, potency, yield, colors etc. — they sometimes accidentally
stabilize other traits like nutrient requirements, smell or taste. Some
breeders point out when their strains need more K or Mg, and this is worth
taking into consideration when choosing your strain and feeding products.
However be suspicious of breeders who claim that you should lower doses
of a specific nutrient or range of nutrients. They could be telling you
to do this in order to justify the floral and leaf color display that
was published in the seed bank catalogue. Nutrient disorders can bring
out nice colors in your plants, but you may be sacrificing yield and potency
in favor of van image' by not allowing the plant to thrive in optimal
conditions. Lack of K can bring out red hues all over your plant. With
some strains this can even turn the bud purple. A few common CaMgS problems
and treatments are described next.
MACRONUTRIENT DISORDERS: A ROUGH GUIDE
Most micronutrients are used by the cannabis plant in such small quantities
that the role they play in plant functionality is quite limited. Also
micronutrient disorders are extremely rare with cannabis plants unless
you are using a completely neutral substrate with no added nutrients.
Most loam soils already contain micronutrients so you do not need to add
much, if any. Good growers, however, will always top up on low doses of
micronutrients because they know that prevention is better than cure.
Macronutrients on the other hand are very important plant nutrients used
widely by the plant throughout its grow. This guide will explain how these
macronu-trients work and how to spot macronutrient disorders in your garden.
Nitrogen (N)
Like most plants, cannabis uses N more than any other nutrient —
especially during the vegetative growth stage of the life cycle. N directly
helps the plant to create chlorophyll, which is used in photosynthesis
for the production of plant energy. Without sufficient levels of N, cannabis
plants turn a pale yellow-green, starting with the bottom leaves and gradually
moving up to the top of the plant. Eventually the leaves wither and fall
off. Lack of N also stunts plant growth.
Phosphorous (P)
Like most plants, cannabis uses P during photosynthesis to create chemical
compounds essential to plant growth, especially floral development during
the flowering phase of the life cycle. Lack of P causes plant veins to
turn red and also stunts plant growth. Foods that are high in P are also
called xBloom'foods.
Potassium (K)
K assists the plant's chemical synthesis and overall metabolism. Some
chemical synthesis processes are used to help fight disease, so lack of
potassium can make your plant vulnerable to plant diseases like mold,
fungi and wilt. K also assists in seed and stem development. Without sufficient
K, stems and branches become weak and break. Necrotic patches develop
on leaf tips at the base of the plant and in blotchy patterns in the middle
of those leaves. Red stems are a sign of a K problem, but red stems can
be a genetic trait in some plants, especially in equatorial strains, and
cold temperatures can cause stems to turn red as well. Be careful not
to misdiagnose these symptoms as a K deficiency and risk overfeeding your
plant.
Calcium (Ca)
Plant cells use and store Ca for cell development. Ca problems are rare
and the symptoms are almost undetectable in cannabis, but if left untreated
they will stunt growth and eventually cause the plant to wilt. If your
plants display stunted growth yet do not display any symptoms associated
with a another nutrient disorder then adjust the amount of Ca that you
are adding to your plants in the feeding plan. To prevent secondary nutrient
problems like our Ca problem here, which are hard to detect, you should
top up on all of the secondary nutrients together.
Sulfur (S)
Like K, S assists the plant's chemical synthesis and metabolism. It is
also used in the creation of amino acids and proteins. Without S, new
growth is yellow and pale looking. The rest of the plant will also eventually
yellow from lack of S. It is important to catch S and l\l deficiencies
early, before they advance to the stage where it is difficult to detect
the actual cause of the problem. l\l disorders run from the bottom of
the plant upwards. S starts at new growth formations and spreads from
there. A severe case of an S deficiency looks exactly like a severe case
of an l\l deficiency, so check your plants regularly to increase your
chances of early detection.
Magnesium (Mg)
Chlorophyll is a group of magnesium containing green pigments that occur
in plants, giving the characteristic green color to foliage and acting
as absorbers of light for photosynthesis. Since Mg is central to chlorophyll
production, the plant needs it to carry out photosynthesis. Plants with
Mg problems exhibit both yellowing and leaf curl, especially leaves that
curls upwards at the base of the plant. This is where the saying —
The plant is praying for magnesium' comes from.
Mg problems are the most common secondary nutrient disorder you will
come across. To correct this, feed your plant 1/3 of a tablespoon of Epsom
salts per three gallons of water every three to four weeks. You should
choose Epsom salts from your grow shop instead of Epsom salts from the
drugstore because the grow shop version is designed for plant use (easier
to break down in water). You also get a lot more Epsom salts for your
money if you buy it in a grow shop. If your soil does not contain Mg,
you will need to use a feeding product that contains Mg. You should be
able to buy secondary feeding products from your local grow shop. They
come either in liquid, powder or granular format. Avoid using granules
because they take more time to break down in the soil. Granule type foods
tend to be ^slow release' foods. 'Formulex' is a good secondary food product
that can be used to correct Mg problems.
Micronutrient problems rarely occur unless there is a problem with lockout.
Lockout is a chemical reaction that takes place with the nutrients in
the soil and can occur if a large amount of one single nutrient is added
or if salt gets into your mixture. Old nutrient formulas can also cause
lockout. It is simply a chemical reaction similar to a precipitation,
which results in the combining of nutrients to form new chemical compounds
that the plant can not use. Lockout is hard to detect. If you have problems
with a disorder that you can not seem to solve by adding more of the missing
nutrient, then you need to consider that this nutrient is locked out.
If lockout does occur you will need to flush your soil. Soil flushing
is described later in this chapter.
Feeding
Feeding is the process of adding nutrients that the plant has removed
back into your soil. We mentioned that you would need a maximum of four
feeding solutions throughout your plants' growth. The first is to be used
during vegetative growth, the second during flowering and the third and
fourth only as needed. Plant food comes in all different forms —
from solids, to liquids, to sprays, to powders, to granules.The most common
form is liquid and this comes in either bottles or large containers.
You should only feed your plants when they need increased nutrition.
Otherwise, you will risk burning them. What this means is that you need
to be able to judge when cannabis plants need food. In the previous section
we looked at certain nutrient formulas and feeding routines, for example
one feeding every seven days at 1/4 strength of what it says on the label
during vegetative growth.
Some cannabis strains will need N more than others. You can detect this
if your plants start to yellow at the base in first few weeks of vegetative
growth. If this happens, reduce your feeding schedule from seven days
to five days, then three, and so on until you solve the yellowing. This
will tell you how often you need to feed your plants at 1/4 strength.
Instead of watering at 1/4 strength* more frequently, you could feed your
plants a higher-strength nutrient mixture, but you increase the risk of
burning your plants this way. Even though plant burn does not usually
kill a plant if you solve the problem quickly, it can stunt and stress
growth.
The amount of feed that you'll use is relative to your growing conditions
and strain. You should never have to feed cannabis daily. In fact, the
most nutrient-consuming cannabis strains should only need to be fed once
every five days at 75% strength. Marijuana plants burn easily so never
mix your solution at 100 percent. We will note some exceptions to this
rule below, but they are very uncommon. In all other situations you should
abide by the rule. If the instructions say to use 1 capful of feed per
gallon of water, then aim for 1/4 strength by using one cap to every four
gallons. If the instructions say to use one capful of feed per two liters
of water and you know that your plants need lots of nutrients then go
for 1/2 strength by using one cap to every four liters of water.
Try not to reduce the cap size in your feeding equation because 1/4 caps
tend to be only enough to feed a plant or two. When you mix plant food
you will want to be able to feed many of your cannabis plants as possible.Three-gallon
watering cans are best for the job if you have six plants or more. It
is possible to burn plants even at half strength, so take care when feeding
and observe the behavior of your plants after feeding. If any of the leaf
edges crumple up and appear dark green/brown and flaky, then you have
probably burned your plants. The only way to solve plant burn is with
a soil flush. We will discuss this procedure later in this Chapter.
There are some situations that call for mixing nutrient solutions at
100 percent strength but these are not common. They are:
1. If you are using 'special' cannabis nutrients. These are manufactured
and sold in some European countries and can be legally imported into many
other countries. You should still take security precautions when buying
and storing these items, however, and make sure that it is not illegal
to purchase or own them where you live. 'Special' cannabis nutrients are
simply normal nutrients mixed at lower strengths so that they will not
burn cannabis.
2. If your solution contains nutrient values of less than 5 percent.
Doses of values lower than 5 percent on the bottle need to be mixed at
higher ratios for some plants. An NPK value of 5:5:5 contains only 15
percent nutrients in the solution; the other 85 percent is usually just
water. At 25 percent strength this nutrient solution will contain low
nutrient values, so a more nutrient-hungry strain should be fed a higher-strength
mixture. Some strains can use a 5:5:5 solution at 100 percent strength
but this is not recommended because of potential plant burn.
3. If your individual plants are extremely large and flowering. Large,
outdoor hybrid strains can consume lots of water and nutrients daily.
In Australia, there are hybrid Sativa strains that grow to near tree-like
proportions. Even though growers take care to ensure that the soil around
the plant is rich in nutrients they may need to feed these plants more
often to improve bud growth during flowering with a strong bloom mix.
A 100 percent solution may help boost the plant but only if the grower
is certain that the mixture will be spread evenly around the base. By
watering in a circle starting from the base of the plant and moving outwards,
the grower can ensure that the strong solution has been distributed evenly
to the area surrounding the plant.The soil around the plant will absorb
the new minerals at 100 percent strength and the roots will find these
as they grow outwards. This kind of 100 percent boost can be good for
large plants.
As a final note to this section it would be wise to point out that you
should never put food directly from the bottle into your plant's soil.This
probably will kill your plant. Always mix it with water first or you could
end up having to perform an emergency soil flush.
SOIL CONTROL
As your plant grows through its life cycle; it absorbs minerals from the
soil and deposits waste material of its own. We have already stated that
cannabis plants need a steady pH level of 7.The removal of nutrients and
addition of waste material can cause soil pH levels to fluctuate.
PH
You should check the pH level of your soil at least once every week and
one or two days after feeding. A pH test kit can be purchased from most
grow shops. Be aware that the electronic test kits can be expensive. pH
test kits are unfortunately the only way to test your mixture's pH. If
you find that your soil's pH has shifted out of the 6 to 8 range you need
to bring the level back to 7. Recall that below 7 is acidic and above
7 is alkaline.There are two ways to adjust the pH of the soil, and these
are described below. You can also perform a soil flush. Soil flushing
is not recommended except for in extreme circumstances, such as serious
pH fluctuations or chemical burns, and is described in detail later in
this chapter.
++ pH - Bringing Back to Neutral from Acidic
If your soil's pH is too acidic you will want to bring it back to a neutral
7. You can do this using lime (alkaline calcium oxide), a brittle white
caustic solid obtained by heating limestone. Lime can be bought in small
containers from any grow shop and added to your soil the next time you
water your plant. Only add small amounts each time, testing the pH the
next day to monitor the effects. You'll find that, over time, you will
get to know your soil and what it needs. Advanced growers know by trial
and error how much lime they need to use to push acidic soil back to a
pH level of 7.
++ pH - Bringing Back to Neutral from Alkaline
If the pH of your soil is too alkaline then you will want to bring it
back to a neutral 7 by adding small amounts of any of the following:
• Cottonseed meal
• Lemon peels
• Coffee grounds
• A high-acidity fertilizer
Always introduce small amounts of the substance, checking the pH level
the next day and readjusting as necessary. Over time, you'll know what
measures to use for different pot sizes and soil mixes.
++ pH up / pH down
Chemical pH products are growing in popularity among professional growers.
They essentially act as a chemical agent for adjusting your soil pH and
are available in most grow shops. They come in two forms: up and down.
There is also a third type of pH solution called a buffer. The buffer
solution is always a neutral 7 and is used to calibrate instruments so
that they read correctly when you use them to test pH.
Both pH up and pH down come in liquid form. pH down contains nitric acid
at roughly 38 percent strength and pH up contains potassium hydroxide
at roughly 50 percent strength. Always check the label to make sure.The
rest of the solution is usually just water. It is not a good idea to use
your pH caps as measuring devices as this could result in foreign elements
being introduced into the pH solution.
To adjust pH, read the instructions on the bottle carefully. It is wise
to use a clean syringe for measuring how much of the pH up or down formula
you need to use but a beaker or plastic measuring jug will do. Carefully
add the recommended amount to water and mix well.Then, add this to your
soil mixture and check your pH level with a reader. In general, 0.5 ml
of pH up or pH down will move the solution by +/-0.1 pH per three gallons
of mixture. A normal size syringe will usually drop out anywhere between
0.1 ml and 0.5 ml at a time.
FOR EXAMPLE:
Say you have a three-gallon pot system and your soil tests at a level
of 5.6 pH. You need to move this up to a stable 7 so you need to go +1.4
pH by using pH up. Here's how to do it. Simply fill a watering can with
three gallons of water and test it using a pH meter to get the reading
of the water. If it is 7 then all is fine. If not then you need to balance
the water to 7 before adding the +1.4 pH up. So if your water has a pH
of 6 then you need to add 2.4 pH up (1.4 pH up + 1.0 pH up) to bring the
soil mixture back to 7 after watering. 2.4 pH up roughly translates to
about 12 ml of pH up. Use a pH reader to test the end results, which should
be +8.4 pH. Simply add this pH-treated water to the soil, which has a
pH of 5.6 and it should balance back to 7 again. Check your soil's pH
a day or two after treatment to confirm this.
pH is important because low or high pH levels can cause nutrient lockout
to occur. pH irregularities can also cause growth stunting, leaf spots
and wilting. Always check the pH level of your soil before treating a
nutrient problem. Another thing to note is that nutrient formulas have
their own pH levels and you can use your pH reader to check a nutrient
solution's pH level. You may need to balance the nutrient pH using the
method of control we have outlined above. Serious pH irregularities occur
in cannabis either when the pH drops below 5.5 in soil or goes above 8.
The normal level of 7 induces optimal growth. It must also be noted at
this point that the pH level and treatment of hydroponic solutions is
very different to soil.
WATER CONTROL
Water your plant at least every second or third day, or better still,
as needed. Never let the soil dry out completely for long periods of time.
The following method works well with good-sized three-gallon pots:
• Day A - water
• Day B - let dry
• Day C - let dry
• Day D - check soil and water if needed
Your watering schedule will really depend on the size of your pots and
soil type. If you pick up your pot when it's dry, then try to pick up
the same pot when it has been watered, you will feel the difference in
weight. This is one way to judge if your pots need watering.
You can detect signs of underwatering and overwatering simply by observing
your plants' leaves. Watch your plants for two to three days after you
have watered them. Do the fan leaves point outward to receive more light
or do they wilt downward? Wilting leaves can be a sign of either underwatering
or overwatering. Check your soil. Is it dry? If so, then add more water.
You may find that you need to water every day because your lighting discharges
a lot of heat and your soil is a quick-draining kind. If your soil is
wet, then leave the soil to dry out until your leaves pick up again. You'll
eventually establish a pattern for your plants' watering needs.
Be aware that overwatering will eventually kill your plants. If this
happens, you can only let the soil dry out and hope for the best. Using
a fan near the surface of the soil is the single best way to help solve
an overwatering problem. Transplants are difficult to do with wet soil.
If you think you need to perform a transplant because of overwatering
then do so — but remember that the soil will be wet and break up
easily in your hands. Try and do the transplant quickly and neatly over
a short working distance.
AIR CONTROL
During the vegetative growth and flowering stages, cannabis plants love
to get fresh air. Bearing in mind security — if you have a window
in your grow leave it open for a while and let your grow room refresh
itself every day. Also, during the dry periods in between watering, the
roots like to breathe. The fresher the air, the better. During winter
you may want to reduce the time that the windows are open as the cold
may stunt growth. Just refresh the air in your room for 15 to 20 minutes
during winter and close it again. If your grow is enclosed, without windows,
then use fans to extract the old air outside and another fan intake to
refresh the system.
Odor Control
To say that we smell with our noses is like saying we taste with our lips.The
nose channels air to our olfactory epithelium, a patch of cells which
reside at the end of the nasal cavity. The olfactory epithelium senses
the different compositions in the air and detects odorous molecules which
gives us the effect of smell.
Cannabis plants continue to release odorous molecules into the air throughout
their life. In vegetative growth the cannabis plant has a detectable odor
which starts around the 1st week of vegetative growth and gradually increases
until the end of the grow. This scent is very unique to the cannabis plant
and can be described as a sharp, pleasingly pungent, freshly cut grass
type of smell. In the flowering stages the plant tends to release numerous
odorous molecules into the air in very large amounts.These scents are
like the freshly cut grass type of smell coupled with fruity, forest,
hash, skunk or chemical type odors. Cannabis naturally has a diverse range
of smells and odors as the result of recombining its genetic material
through natural selection and breeding (see Chapter 15).
You must deal with odorous molecules before they leave the grow room if
you wish to prevent cannabis smells from traveling. Cannabis growers have
found three ways to deal with this. These are:
• Ionizing • Ozone Generating • Activated Carbon Air
Filtering
Ionizing
Ionizers are air purification systems that control - odors, smoke, mold,
bacteria, chemical gases, mildew, stale air, pollen, dust and static electricity.
Air ionization systems work by outputting negative ions into the area
they are operated in. These negative ions are used to neutralize odor
molecules that are in the air.The ions will attract the odorous molecules
to them and when attached to the odorous molecule will deactivate the
odor molecule by neutralization. Some ions will cause the odorous molecules
to fall to the ground so that they will not remain airborne. The problem
with ionizing is that these deactivated particles and negative ions tend
to stick to surfaces such as the floor, pots, plant leaves, walls, lights,
reflectors, ballasts and ducting. Some of the deactivated particles may
be extracted by the outtake fan but your grow area will require cleaning
every month if you use an Ionizer.
Ionizers are cheap to buy but are only suitable for smaller growing operations
where up to six medium sized plants are concerned. Growers still use them
but there are better options of odor control available to you.
Ozone Generating
Ozone is also known as activated oxygen. Activated oxygen contains three
atoms rather than two which is what we normally breathe. Ozone is a very
vigorous sterilizer. Ozone can be found in nature but we can also buy
units that generate ozone. Ozone has a lifespan of about 30 minutes. When
ozone (03) comes in contact with odorous molecules, one of the ozone atoms
detaches itself from the ozone and attaches itself to the odorous molecules.
This oxidizes the cell walls of the odorous molecules which eventually
destroys the odorous molecules leaving only oxygen behind.
Ozone does have some setbacks. Too much ozone is not good for plant health
or human health although most ozone generators are specially adapted to
render the health risks of ozone obsolete. The legal exposure limit for
human beings is around O.lppm for a maximum of eight hours. Ozone generators
that are used for horticultural purposes tend to only generate 0.05 ppm
and a timed rate so that exposure is kept to a minimal amount.
Ozone generators are better at controlling cannabis odors than Ionizers.
Activated Carbon Air Filtering
Activating carbon is the safest most effective way of dealing with cannabis
odors and is part of any professional grow room. Charcoal is carbon. When
we treat charcoal with oxygen it opens up millions of pores in the carbon
atoms. This type of treated charcoal is known as activated charcoal and
is the main ingredient of our activated carbon filter. The activated charcoal
is usually broken down into pellets so that it can be used with air filtering
units.
Activated charcoal absorbs odorous molecules by chemical attraction.
The activated charcoal is contained in a metal tube with filters screening
the air that passes through.
The whole unit is called an activated carbon filter and is attached near
your out-take vent. Not all activated carbon filters use charcoal. Some
activated carbon is made from the husks of coconuts. Activated carbon
filters need the carbon changed every couple of months. You will know
when to change the carbon if it no longer filters out odorous molecules.
Activated carbon can be found in most good filter supply stores. Make
sure that you choose activated carbon pellets. There is another form of
activated carbon called crushed activated carbon but this is not as effective
as the version that comes in pellet form.
VENTILATION
Ventilation is a very important aspect of indoor environment control.
Most cannabis flowers are sticky. Dust sticks to bud. So your ventilation
system must not be allowed to blow dust into or around your grow room.
This is simply done by keeping the grow room clean and making sure that
all air intakes are equipped with screens. You will have to clean the
screens every so often to maintain a clean air flow into your grow room.
You will also need to ventilate your grow room if it gets too hot for
your plants. This is the primary reason why most growers need a ventilation
system.The other reason is to prevent the humidity from increasing in
the grow room, which can cause mold and other plant problems. Fresh air
also contains gases (oxygen, nitrogen, carbon dioxide and traces of other
gases) some of which are used up by the plants in the growing environment.
This causes levels of these gases to fluctuate in the grow room. If a
grow room does not have adequate ventilation then these gases will not
be replaced and this causes problems with plant health. In order to provide
optimal conditions for cultivating cannabis we must have a well ventilated
grow space.
All good growers spend time getting their ventilation right before they
start their grow. Here is a list of reasons to have a good ventilation
system in your grow room.
1. To prevent mold.
2. To replenish various gases in the air.
3. To stabilize humidity.
4. To control air flow.
5. To boost yield using a slow release carbon dioxide system (covered
at the end of this Chapter).
There are two main components in a ventilation system: the passive intake
(air in) and the vent (air out). The vent should be located high up in
your grow room because hot air rises. The vent should come equipped with
a fan to push air out through the vent. Odor control devices (activated
carbon filters, charcoal filters) are usually attached to or located near
the vent.
When the fan has sucked all the air out of the room through the vent,
it will create a vacuum. Air will need to get back into your grow room
again so it will find any way in that it can. Holes in the walls, frame
and roof are all vulnerable spots where air can be pulled in. Since we
want our airflow to be under control we need to make sure that all false
air intake spots are sealed first.
The passive intake (with a screen to prevent dust from getting in) should
be installed low in the grow room so that, as air is brought in from outside,
it passes through, around and over the plants. This air will help to cool
the plants and the space between the lighting and the cannabis top colas
before finally being extracted by the vent. Dust will also be forced out
the vent. Passive intakes do not require a fan but some growers do use
them to regulate how much air enters the room.
Nearly every cannabis grow room uses the above scenario for ventilation.
Spend time designing your ventilation before you set up your grow room.
The cost of setting a good system up is much lower than you think. Air-cooled
hoods for HID lights need to be used in conjunction with a vent.
Fans
Fans can be placed quite close to mature marijuana plants and a slight
breeze helps them to develop stronger stems and branches. Fans also circulate
the air around your plants, simulating an outdoor environment. A fan's
ability to 'move' air from one location to another is measured in cfm
(cubic feet per minute). You should aim to replace the air in your grow
room at least once a minute. If your room is hot then you may need to
remove the air in your room as much as five times a minute. On average,
growers use a fan with the capacity to circulate the room's air three
times in one minute.
FOR EXAMPLE: If your grow room is 2 X 5 X 5 then it is 50 cubic feet
in size. For this grow room you need a fan that ranges somewhere between
150 cfm (3 X 50 cfm) and 250 cfm (5 X 50 cfm). In this example, the 150
cfm fan can move all of the air out of the grow room 3 times per minute.The
250 cfm fan will do it five times a minute. The rate at which you want
the air to be removed from your grow room depends on:
• How hot it gets inside the room.
• How cold the air outside is.
• If you are using C02.
You can find the xcfm' written on the side of the fan. Squirrel cage type
fans are highly recommended.
Sometimes a very good air extraction system causes areas of the grow
room to receive less of the new air than others. If you want to ensure
that all areas of the grow room receive adequate amounts of fresh air
then use a regular domestic oscillating fan. Oscillating fans also help
to build up thick stems and branches.The speed at which you set your fan
depends on how much the plants move. Plants like movement but too much
can make them uproot or fall over. Use common sense with these type of
fans.
HUMIDITY
Cannabis plants grow best under conditions between 40 and 80 percent relative
humidity (rH). rH is the amount of water in the air. Introducing fresh
air into the environment is the best way to control humidity. In short,
if you have installed a good air circulation system then you should not
have a problem with the humidity in your grow room. If your air has a
high humidity level then you will need to purchase a dehumidi-fier. These
expensive items are used to control rH in the room. They do this by simply
cooling the air that travels through the unit causing it to condense and
loose some of its water vapor.
Cannabis grows well at levels of between 40 percent and 80 percent rH.
If you have a rH measuring kit you can judge for yourself how much fresh
air you need in order to achieve the optimum 60 percent level. These measuring
kits are also expensive to buy and usually have to be ordered in by your
local grow store. Good cannabis growers try to avoid the cost of dehumidifiers
and rH monitors by simply installing a good air circulation system from
day one.
TEMPERATURE
Cannabis likes the same temperature that people do, so the best meter
for temperature control is you. If you find it's too cold in your grow
room, so will your plants. Under normal circumstances, room temperature
is easily controlled by thermostat, but in your grow space, lighting will
impact on temperature. You should aim for 75 degrees Fahrenheit, but slightly
warmer temperatures do help plants to grow a bit more quickly.
Monitor your room's temperature with one or more thermometers. Hot air
rises so you can expect that the temperature of the air above the thermometer
will be hotter than the air under it. Using more than one thermometer,
you get an idea of the temperature ranges in your room (at root level
and canopy or light level).
You do not want to go above 85 degrees Fahrenheit. If you do, you will
only heat stress* your plants and stunt growth. Going above 125 degrees
Fahrenheit can kill cannabis but this depends on the strain. Some equatorial
strains can still grow at 125 degrees Fahrenheit as their genetic make-up
can withstand it. In order to cool the room, you will need to ventilate
it either by opening a window or installing a ventilation system, as described
above.
During the flowering phase of the life cycle you will after the photoperiod
to what is called 12/12. The procedure known as 'changing the photo-period
to 12/12' is explained in detail in Chapter 7. 12/12 means that for 12
hours your grow room lights will be on and for the next 12 hours they
will be switched off. Since bulb heat contributes to the grow room's temperature,
the temperature will drop when the lights are out- During the dark periods
of the flowering phase the temperature is allowed to drop down as
far as 55 degrees Fahrenheit. You should prevent temperatures going lower
than 55 degrees at night because this stunts growth. Below 30 and you
can expect serious plant damage. If the temperature does drop below 55
during the dark period then you need to heat the grow room. The best way
to do this is using an electric heater. For an average-size grow room,
a small, portable heater that plugs into a domestic socket will do.
TIMERS
Timers are important devices for controlling when lights, heaters, fans
and any other electrical units in your grow should be switched on or off.
Some lighting kits, ballasts and fans come with built-in timers. If you
do not have a built-in timer you can buy one from any good home electrical
store or grow shop. Timers simply act as a regulator between your power
source and the device that needs the electricity. You plug your device
into the timer and then you plug the timer into your electrical output.
Some timers have a digital display and others have an analog display.
Simply set your timer to turn on when you want the device to turn or and
to turn off at the time you want your device to turn off.
Timers should not be overloaded. Current must pass through the timer unit
so you may need to use multiple timers in your grow room. To understand
your timer'; limits consult the manual that comes with it.
C02 (CARBON DIOXIDE)
C02 is a gas that helps promote plant growth, especially floral growth.
About 0.03 percent by volume of the Earth's atmosphere is made up of carbon
dioxide. Carbon dioxide is natural and not harmful. Plants absorb carbon
dioxide from the air and use it for photosynthesis. If the supply of carbon
dioxide stops, so does the process of photosynthesis. Increasing the supply
of carbon dioxide increases photosynthesis.
Millions of years ago there was much more carbon dioxide in the atmosphere.
Somehow plants have still not lost their ability to process high doses
of carbon dioxide which leads to lots of plant vigor at a faster speed
of growth. The atmosphere on Earth today is different and has slowed down
plant development — you could say that we have a planet full of
underdeveloped plants!
Plants will use carbon dioxide in any growing environment. Using a simple
air circulation system in your grow room will help replenish the carbon
dioxide the plants have used. If you want to increase plant size, yield
and vigor, and speed up growth you need to look closely at increasing
carbon dioxide levels.
Carbon dioxide can triple yields. A one-ounce plant can quickly become
a three-ounce plant but this depends largely on the plant's genetics.
Every cannabis strain has a genetic threshold for bud production. It will
not exceed that limit, even under optimal growing conditions. Introduction
of supplementary carbon dioxide ensures that your plants will hit their
optimal rate of growth. You do not need supplementary carbon dioxide to
grow high-yielding plants but the noticeable effects on the speed and
quantity of bud production with supplementary CC-2 places the gas in the
same category of importance for high yields as 'plant genetics' and Might
source'.
Carbon dioxide "generators' are expensive industrial units that
burn fuel to produce carbon dioxide. Although you can buy different types
of generators that use a range of diverse fuel sources, they are really
only suitable for very large indoor or greenhouse growing operations.
Most growers who use carbon dioxide in their grow room choose aHimed release'system.This
is simply a unit that releases a certain amount of compressed carbon dioxide
from a tank at a timed rate of release.
Carbon dioxide tanks can be bought and refilled at any good welding supply
store. It is best to use a welding supply store over any other type of
store when you acquire carbon dioxide. If anyone asks — you are
welding something. They ar also the perfect place to refill your carbon
dioxide canisters. Carbon dioxide ca also be purchased from most 'fuel
depots'. The tanks come in different shapes am sizes but you should aim
for multiple 20-pound tanks or the 50-pound type if yoi have a lot of
grow space. We will calculate exactly how much carbon dioxide t< introduce
into your growing environment in the next section. Twenty-pound tank;
are easier to lift, move and fit into your grow room. Also, using multiple
tank: allows you to refill on carbon dioxide while the other tank is releasing
carbor dioxide into your grow room. Once you have a tank of carbon dioxide
you need tc purchase a tank regulator (an infrared sensor or combination
flow meter will alsc do) and a timer. The tank regulator controls the
quantity of carbon dioxide emitted and the timer controls when the gas
is released.
Calculating How Much Carbon Dioxide You Need
How much carbon dioxide you need is quite straight forward but requires
a bit o information about your grow room and ventilation system. Here
are the steps yoi need to take:
1. Calculate the volume of your grow in cubic feet by multiplying the
length x width x height of the room.
2. There is already carbon dioxide present in the room. It should be around
300 ppm (parts per million). The optimal level for cannabis is 1500 ppm.
You will need to increase carbon dioxide levels by 1200 ppm.
3. Multiply the grow room in cubic feet by 0.0012 to find out how much
carbon dioxide you need to supplement your room to 1500 ppm.
FOR EXAMPLE:
1. A 10 x 10 x 10 room is 1000 cubic feet in size.
2. 1000 x 0.0012 = 1.2 cubic feet.
3. 1.2 cubic feet of carbon dioxide will be needed to bring this room
up to 1500 ppm.
If you have an air-circulation system in your grow room you may wish to
reducd the speed of your fan to prevent carbon dioxide from being vented
too quickN (after all you are paying for it and you don't want to waste
too much of it). If you reach 1500 ppm for carbon dioxide in your grow
room you are allowed an increase of temperature to 95 degrees Fahrenheit
because the increased carbon dioxide allows cannabis plants to grow in
these temperatures without stressing them. If this does heat stress your
plants then try to increase your ppm to 2000 which should be better for
your plants in temperatures of 95 degrees Fahrenheit. If you find that
slowing down the vent fan to keep carbon dioxide in the room is still
causing your plants heat stress then you simply need to regulate how many
times carbon dioxide is released into your system with every air change.The
more often air is vented out, the more carbon dioxide you need to release.
A hose can be used in conjunction with the regulator to ensure that the
carbon dioxide escapes at a point that is furthest away from your vent.
This ensures that as many plants as possible get access to the COa before
it finally is vented out.
Remember that heat stress stunts growth, voiding the benefits of any
carbon dioxide supplement. Get your air circulation right before you introduce
high levels of carbon dioxide into the grow environment. A good air circulation
system should be flexible enough to allow for a slow carbon dioxide release
system to work. It is just a matter of controlling the timing of the release,
the amount to be released and how much air must be moved out of the grow
room in order to keep it within a certain range of temperatures. During
12/12, carbon dioxide is turned off for the dark period, because without
light there is little photosynthesis.
CLIMATE CONTROLLERS
These devices serve multifarious tasks in the grow room. Much like a timer
they regulate the activity of the electrical device(s) they are connected
too. Climate controllers also go by the names of: environment controllers,
climate monitors and climate sensors. They come in both analogue and digital
formats. The more expensive the climate controller, the more functions
it has and the more devices it can control. Climate controllers can be
used to regulate the following systems in your grow room:
LIGHTS
VENTILATION AND EXTRACTION
C02 DISBURSEMENT
HUMIDITY
PUMPS
The climate controller is usually fastened into your grow room wall.
The devices that the unit is controlling plug into the separate slots
of the climate controller. The controller itself is then plugged into
your electrical mains and turned on.
Expensive climate controller are self-regulated and come with built-in
sensors that detect when the controller should be activated for a specific
task or a set of tasks. You set how it controls those tasks, with the
setting of the controller.
By way of example an advanced climate controller can be setup to do the
following:
During the photoperiod the climate controller regulates the 12/12 pho-toperiod
by turning the lights on for 12 hours and off for 12 hours. The controller
monitors the heat in the room, which will vary when the lights are on
and off.The heat sensors of the controller adjust the speed of the extraction
fans to accommodate for the change in heat to meet your settings. If the
temperature drops below your established temperature the controller turns
on the heating device that you have attached to it to meet your fixed
temperature or temperature range. At the same time the controller can
also regulate C02 systems and Humidifiers in the grow room.
How much you want to spend on a controller depends on how many devices
you want it to control and how much control you want over these devices.
There are many controllers available to suite small to large tasks.
C.A.P, is a popular manufacturer of climate controllers and they have
a product range varying from simply controllers for small grow rooms to
full size greenhouse controllers. Consult your grow store for details
on the type of the controller you are looking for. Basic controllers start
at around $60.00 and expert controllers can cost up to $2000.00
60 Indita/Sativa hybrids in ttie final week before harvest.
SOIL FLUSHING
A soil flush is a last resort when all else has failed, as in the following
scenario.
In this hypothetical situation, you are using a soil that holds a lot
of water and you want to feed your plant. You take out the appropriate
feeding bottle, add it straight to your plant and pour the water in after.
(This is never recommended. Always mix your plant food with water in a
container, such as a jug or watering can, before administering it to your
plant.} As you move to pour the correct dose over the soil, your hand
shakes and the bottle spills. The next thing you know, half of your raw
feeding liquid has managed to find its way into the soil. You curse yourself
for not following the instructions. What should you do? You pick up this
book and turn to this page. You read about the soil flush and see that
your plant still has a slim chance of survival. You know that all the
raw chemicals could kill your plant and this is your last resort.
Here is how to flush your soil. ++ STEP A.
(1) Take the potted plant to a sink.
(2) Turn the plant on its side, making sure not to bend or break the stem.
(3) If you think the stem will break then find a long stick and place
it in the soil, use thread to secure the plant to the stick at several
points and secure the stick to the pot.
(4) Tilt the potted plant on its side so that the top of the pot with
the soil is facing at an angle toward the sink.
(5) Do this until all the liquid has poured out, noting the color of the
liquid that runs out. Some nutrients will dye the water a pink, brown
or yellow color. You may see a hue to this water coming out. When this
changes color after the flush you know that all the nutrients are flushed
out. If the nutrient does not dye the water you can still continue the
flush. Just pour everything out.
++ STEP B.
If your pot is perforated continue. Otherwise, proceed to Step C.
(1) Pull your plant back up and sit it in the sink.
(2) Pour lots of water on top of the soil.
(3) Wait until the water flows out the bottom of the pot, observing the
color of the flow as in step A.
(4) Repeat this process until the color of the water becomes clearer.
The soil will get very muddy when you do this and some of the mud will
pass out with the water. Try and keep hold of as much of as it as you
can.)
(5) Once the water runs clear tilt your plant on its side again and wait
for all the water to drain out.
(6) If your feeding solution doesn't have a color then flush water through
the plant a number of times to ensure that all the nutrients are flushed
out.This usually takes about seven flushes with a three-gallon pot. Remember
that if you see color change then all your nutrients are flushed out and
you do not need to flush anymore.
(7) Quickly take your plant to a warm, dry area and wait for the soil
to dry out.
(8) Proceed to Step D.
++ STEP C.
(1) You can use a screwdriver to make holes in your pot if it is made
of lightweight plastic. You can always use thick masking tape later to
patch the holes up. If you do this, then follow Step B. If you can't do
this, then you need to perform an emergency transplant.
(2) Prepare a new pot with soil, leaving a large gap in the middle where
your plant will go.
(3) Take your plant and use a knife to cut around the edge of the soil
as close to the rim of the pot and as deep as you can.
(4) Put your fingers in down around the inside of the rim and gently pull
the plant and soil out of the pot. Try not to damage the roots.
(5) Hold the soil over the sink and place it down near the drain holding
it together with your hands. If your root mass is big you may need help.
(6) Turn on the water and let it run slowly down over the soil.
(7) Keep holding the plant for a number of minutes until you see a change
in the color of the water that's coming from the soil. Do not crush the
soil just hold it. It will get muddy and will break up a bit, but this
is to be expected.
(8) When the water changes, place the plant into the new pot.
(9) Fill up the spaces with new soil and use a stick to prop up your plant
if needed.
(10)Quickly take your plant to a warm dry area and wait for the soil to
dry out.
(11) Proceed to Step D.
STEP D.
(1) Every day measure the pH of the soil. If you have flushed your plant
properly it should return to the near 7 mark (given that the water you
use is a neutral pH of 7).
Sadly, few plants survive such an emergency soil flush.The soil flush
is, in essence, overwatering your plant to the point of removing most
of the minerals and ingredients in the soil. If your plant manages to
pull through, you have done well. If your plant doesn't then you'll know
better next time. A soil flush causes the plant a great deal of shock*
and should only be attempted as a last resort if your plant is dying and
can't be cured by any other means. If your plant survives, it ma: have
sustained some damage. If any of the leaves are burnt or look dead you
cai remove them by clipping them away. These damaged plants usually take
abou two weeks to return to full health.
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