7
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 (NPK)? These macronutrients are the primary ingredients needed in soil to ensure a healthy marijuana crop. In addition, the secondary supplements calcium (Ca), magnesium (Mg), and sulfur (S), 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 (CI), manganese (Mn), copper (Cu), zinc (Zn), cobalt (Co), and molybdenum (Mo).These eight micronutrients are less important for good plant health than 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 judgment. 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 some, add them in very small doses (no more than 1/8th 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 second 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 immensely reduces the risk of plant burn.
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 such as 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.
Single pack container. You can also have twin containers or single pack bottles.
Twin pack. You can also have single pack bottles or twin containers.
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 in accessing the other N and K nutrients that it also needs for vegetative growth (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 has 10:0:10 on the label. 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—An example of a balanced vegetative primary nutrient pack.
2. N10:P20:K10—An example of a flowering primary nutrient pack.
3. N0:P20:K10—An example of a flowering food without N.
4. N10:P0:K10—An example of a vegetative food without P.
5. N10:P20:K20—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. Ca1:Mg1:S1—An example of a balanced secondary food.
7. Ca2:Mg3:S4—An example of a secondary food.
8. N10:P10:K10:Ca1:Mg1:S1—An example of bottle of food that contains both primary and secondary nutrients.
9. N10:P0:K0—This is a pure N supplement.
10. N0:P10:K0—This is a pure P supplement.
Micronutrients are sometimes listed in ratios like NPK values, but it is more common to just find micronutrient measurements. One good brand of micronutrient that is used by nearly every grower is called Formulex.
Growers should ensure that at least some secondary nutrients are added to the soil mix or put 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 disorder, such as: leaf discoloring, rusting, blotching, leaf curling, or any other chlorotic 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 N, 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 an 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 “an 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 macronutrients 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 “bloom” foods.
Here a nutrient deficiency looks likely as some leaves are pale and collapsing, though pest attacks can cause plants to have a similar appearance. Both potential problems need to be investigated to determine the real cause.
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 signs 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 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 N deficiencies early, before they advance to the stage where it is difficult to detect the actual cause of the problem. N 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 N 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 (and is thus 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 cannot use. Lockout is hard to detect. If you have problems with a disorder that you cannot 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 back into your growing medium that the plant has removed. 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—solids, liquids, sprays, powders, and 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, or 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
1 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.
Blood meal is a popular organic feed for vegetative growth.The NPK values are clearly seen on the front of this bag. Note the big N value.
Bone meal is also a popular organic feed for flowering. Note the big P value. Organic growers will use bone meal to promote root 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 3/4 strength. Marijuana plants burn easily so never mix your solution at full strength. (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 one 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 as 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 or 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 full 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 full 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 full 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 will probably 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
• 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-sized 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 and is covered in Chapter 9.
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 1: water
• Day 2: let dry
• Day 3: let dry
• Day 4: 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.
There are many watering devices out there. This is a watering wand, which has a variety of nozzles to control the watering spread.
A fan strengthens plant stems by bringing out their natural adaptation to wind resistance. It also creates import airflow.
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 give 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 freshly cut grass 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).
Carbon filters control all odor problems and smells.
Carbon filters are attached to extraction fans.
There are many types of odor control devices available like this odor stop.
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 in which they are operated. 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. Large-scale growers still use them but there are better options of odor control available.
Ozone Generating
Ozone is also known as activated oxygen. Activated oxygen contains three atoms rather than two—the amount which 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 attach-es to the odorous molecules. This oxidizes the cell walls of the odorous molecules which eventually destroy the odorous molecules, leaving only oxygen behind.
Ozone generators are also another way of removing odors from the grow room.
Ozone does have some setbacks. Too much ozone is not good for plant 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 0.1 ppm (parts per million) for a maximum of eight hours. Ozone generators that are used for horticultural purposes tend to only generate 0.05 ppm and at 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 outtake 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).
Ventilation systems can be quite sophisticated.
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 plants’ 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.
Doing it right improves your dank. Colas are bending over from their weight. These genetics are being pushed to the limit.
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. Other ventilation methods are described in chapter 8.
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 per 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 2x5x5, then it is 50 cubic feet in size. For this grow room you need a fan that ranges somewhere between 150 cfm (3x50 cfm) and 250 cfm (5x50 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 CO2.
You can find the cfm 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 types 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 dehumidifier. 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 lose 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.
Hot air rises. Having extraction at the top or near the lights is the best way to get rid of the heat.
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
2 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 alter the photoperiod to what is called 12/12. (This procedure 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.
The hand heat test. If your hand feels discomfort then so will your plants.
An analog display. Large and clear.
Digital display. More accurate with extra features but usually harder to read.
Analog dial timer. Cheap but harder to read.
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 on 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’s limits, consult the manual that comes with it.
CO2 (Carbon Dioxide)
CO2 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, depending 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 CO2 places the gas in the same category of importance for high yields as “plant genetics” and “light source.”
Expert timer for commercial scale grows.
Some serious bud enhanced by CO2 production.
CO2 Regulator.
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 a “timed 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 are also the perfect place to refill your carbon dioxide canisters. Carbon dioxide can also be purchased from most fuel depots. The tanks come in different shapes and sizes but you should aim for multiple 20-pound tanks or the 50-pound type if you have a lot of grow space. We will calculate exactly how much carbon dioxide to introduce into your growing environment in the next section. Twenty-pound tanks are easier to lift, move, and fit into your grow room. Also, using multiple tanks allows you to refill on carbon dioxide while the other tank is releasing carbon dioxide into your grow room. Once you have a tank of carbon dioxide you need to purchase a tank regulator (an infrared sensor or combination flow meter will also 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 straightforward, but requires a bit of information about your grow room and ventilation system. There are two steps:
1. Calculate the volume of your grow in cubic feet by multiplying the length x width x height of the room.
There is already carbon dioxide present in the room. It should be around 300 ppm. The optimal level for cannabis is 1,500 ppm. You will need to increase carbon dioxide levels by 1,200 ppm.
2. Multiply the cubic foot size of the grow room by 0.0012 to find out how much carbon dioxide you need to supplement your room in order to hit 1,500 ppm.
For example:
1. A 10 x 10 x 10 room is 1,000 cubic feet in size.
2. 1,000 x 0.0012 = 1.2 cubic feet.
An all in one plant Environmental Controller.
1.2 cubic feet of carbon dioxide will be needed to bring this room up to 1,500 ppm.
If you have an air-circulation system in your grow room you may wish to reduce the speed of your fan to prevent carbon dioxide from being vented too quickly (after all, you are paying for it and you don’t want to waste too much of it). If you reach 1,500 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 2,000, 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 CO2 before it is finally 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 name of: environment controllers, climate monitors, and climate sensors. They come in both analog 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
• CO2 disbursement
• Pumps
• Ventilation and extraction
• Humidity
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 controllers 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.
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 photoperiod 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 CO2 systems and humidifiers in the grow room.
A sophisticated multipurpose digital green house controller.
Even connoisseur plants can improve their already gorgeous looks with better environmental conditions 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 suit 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 $2,000.00
Soil Flushing
A soil flush is a last resort when all else has failed, as in the following scenario.
While a soil flush may be considered a last resort, it can be a very effective one. The curative properties of water may keep your hard work from going down the drain.
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 this in the water coming out. When the water runs clear, 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 of 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 to keep hold of as much of 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 light-weight 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 a 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 (assuming 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 nutrients in the soil. If your plant manages to pull through, you have done well. If your plant doesn’t, then you know better next time. A soil flush causes the plant a great deal of shock
3 4 5 6 7 8 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 may have sustained some damage. If any of the leaves are burnt or look dead, you can remove them by clipping them away. These damaged plants usually take about two weeks to return to full health.
