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  1. The Indoor Garden Environment  - Part 1 - Location
  2. The Indoor Garden Environment - Part 2 - Temperature
  3. The Indoor Garden Environment - Part 3 - Humidity
  4. The Indoor Garden Environment - Part 4 - Air Quality & CO2
  5. The Indoor Garden Environment - Part 5 - Ventilation & Calculators
  6. Advanced Section I - Understanding light, photosynthesis and how to select grow lighting
  7. Advanced Section II - Lighting & Reflector Section
  8. Advanced Section III - Plant Growth and Light
  9. Advanced Section IIII - Understanding Light Measurements
  10. Advanced Section IV - Advanced Lighting Information and formulas.



The Indoor Garden Environment

~A Cultural Healing and Life Compilation and Writing.


Emoticons are safe bonus links, most youtube, click them.




Environment Introduction


Garden order of importance 

Quality and strength of light + garden environment + nutrition + management/technique/method = grow operation. 


It is not rare for new gardeners to make basic errors when designing or planning an indoor garden.  They often think of the harvest and what the optimum level for this and that when creating a grow environment but they rarely take into genuine consideration the plants themselves when planning and building grow environments.  The following is my attempt to answer this aspect.  First, lets change our perspective to that of the plants.

For many of these plants the indoor garden environment is all they will ever know of nature and life.  By creating a garden environment worthy of this aspect you not only respect the harvest you desire but the life that produced the harvest for you and in so doing we co-exist together in a sacred life cycle harmony that for some is a serious perspective and for others the basics will do.  This is my attempt to lay the groundwork for either direction and all the ways in between.

When we properly respect our plant partners and the harvest (by harvest I mean managing the crop) the happiness along with the fitness of the plant combines to bring back to you in a tangible form a glorious harvest worthy of the life and harvested crop that you have provided and managed for.  To some this is sacred, to others this is just taking care of a plant.   

A plant that is in synergy with its environment, light and nutrition is a healthy and happy plant.  When this happens the best of the genetics is possible by promoting the plants during their life stages or just take an easy growing approach it is all up to you.

  • Note; Sometimes when a plant is in too good an environment we may have to alter the environment to induce a degree of stress to encourage the transition and/or to ripen or potentially face extended grow periods.
    • Certain conditions can affect plant physiology such as hormones and trigger the beginning or the encouragement of a development period.
      • Aspects such as temperature and humidity followed by light timings for quality to life cycle for various plants and qualities there of.


To be wise in creating a garden environment is much more than construction and math.  It is to understand and appreciate the life and physiology of plants, environmental aspects and all those as aspects as a whole. 

  • When these aspects are aligned the full spectrum and strength of your lights will be happily received and they will fittingly energize achieving plants that most will think they could not achieve prior to this appreciation.

In the gardening community we often are more unwise at some point in our gardening lives.   Early in our learning/experience we can tend to prescribe plant problems and aspects incorrectly as to other causes and effects than those that are environmental based or at least in part based. 

  • This misunderstanding often affects the reality of what we actually know of gardening compared to what we think of we know. 
    • At "common and harmless" levels it is just maybe a bit humbling to be corrected or to just learn correctly on a subject that you believed was one way but in fact was another reason or effect of. 
    • At worst, it directly causes harm to yours or others crops. 
  • Market affect on this type of grower:
    • Before spending one bit of money or energy on adding "boosters" and such from light to nutrition unless your garden environment is happily in balance with your plants  or you have largely wasted (ineffective results) and increased the cost of your environment.
      • Their is a difference between a not as healthy plant but normal looking plant gaining health than a very healthy plant gaining a "boost.' from an additive or such.
        • Most people fall into the category of "not as healthy but normal looking plant gaining health."
          • This an aspect why many forums will say boosters do not work, I comment on environment not boosters in general but use as illustration.  

We will be discussing each aspect that makes up the grow environment so that you will be able to influence and manage your environment effectively for each stage of plant growth or just the general grow period as up to you.

  • We will discuss standard grow area sizes and locations associated with personal medical grow rooms and indoor gardens associated within the normal garden community.   
    • In this discussion we will be giving recommendations that represent store bought or easily assembled products. 
      • This is not a marketing gimmick nor an endorsement of any products as they are used for illustration purposes and to be realistic to what I believe many in this category will use, at least initially.
        • I do not give endorsed views other than possible situations based on unique and/or specific needs and availability of products to a perspective gardener.


Grow Environment Formula

Location (Grow Area)


Operational Temperature  (actual operating temperature)

(Day - High & Night - Low)

(To estimate ambient temperature + estimated operational temperature, take into consideration fans, lights, CO2 burners)






Air quality


Climate Adjustments

(CO2, HVAC adjustments in addition to normal ventilation)

  = Grow Environment for Day and Night, can customize for each plant stage of development.





Home Location Selection and Analysis

Location location location as they say.  We all think of grow areas differently.  For some, it is a tent, for others it is an attic, a basement, a closet or just a room.  Regardless of location we have to take some key aspects into consideration and then we want to work on removing any limitations to making a grow location suitable for a plant to call home, as everyone knows "home is where you make it."

Many indoor gardeners do not really select or choose a grow area than they tend to use what is available to them.  Regardless of how we may select the grow area, we need to understand the area wisely.  This is often an aspect that many people take for granted and not much effort is put into effectively appreciating this aspect and often a price is paid for this lack of competence. 

Once a location is chosen and analyzed it needs to be cleaned and prepared correctly. 

  • "Best practice" may be to create a room within the room as to enable the typical construction of a sealed room easier, cleaner and more efficient.
  • Thick or insulated type of walls are best for maintaining stability.
    • Thick walls like rock.
    • Modern insulated walls.
  • A tent is generally not a significant issue as it is affected by the ambient room temperature for which the tent resides.
    • Generally I dislike tents but they are fine to use and have their use depending on a variety of needs.
    • Tent is influenced by the surrounding air in the room.
      • Use air around tent like a lung room.
  • Determine your base ambient temperatures.
  • Determine Cubic Square Feet of grow area
  • Address location negatives
    • Understand the grow area ambient temperature during the seasons and with day and night temperatures.
      • This is your base ambient room temperature.
        • Base Ambient Room Temperature = The "empty" grow area in Day (high) and night (low) for each season.
          • We will use these base high and low numbers in our future calculations and analysis, notice the word and.
    • Basements and attics may have damp and mold that needs cleaned and addressed.
      • Window areas in attics often need addressed.
      • Attics are typically not well insulated and the base ambient temperatures usually vary with the seasons
        • Mostly effected by high and cold temperature extremes.
        • This is one reason an attic garden is less favored unless it favors condition for a particular plant type.
      • Basements may have mold aspects
        • Using mold resistant white paint is an option.
          • Hospital paint that has anti mold/fungus properties.
          • I recommend use in grow areas regardless for "best practice" aspect.
          • Basement base ambient temperature should be stable throughout the year.
    • Flooding issues
      • Old or not well managed drains
        • Address tree root maintenance for pipes if applicable.
    • Bugs/pest issues.
      • A thorough cleaning and competent bug management is typically sufficient.
        • Definitively remove any pre-existing infestations and ensure their will be no return.
      • If the location was previously used for growing then ensure to clean and sterilize for pollen, bugs and molds.


Good Location Video information.


Location Summary

Regardless of where and how we select our garden areas.  It is our job to create and manage a favorable environment as possible for the harvest.  It just so happens to get a good harvest we have to have healthy plants. 

The following information is about various aspects of the environment and how to manage for the location for which your garden resides.  Since the best answer for some situations can vary from situation to situation it is important to understand the flexibility ventilation and its various setups that offers various management and control over your environment and plants.  Remember, no matter the gritty appearance of a starting location you are creating a home!





Temperature & Gardening

To be wise in regards to temperature in gardening is to appreciate that temperature affects two main aspects in the garden.  The environment and the plant.  In gaining an appreciation of these two perspectives and their cumulative and lasting effects is the beginning of taking control of your garden environment rather than your gardens environment controlling you. 

Once we understand this concept we can discuss how to control the environment to our advantage to limiting adverse uncontrollable situations like heat waves or periods of high or low humidity. 


The below formula is made to help illustrate this aspect.  

Temperature/humidity effects on environment + Plant physiology/effects = Temperature in gardening knowledge



Temperature perspective in regard to the garden environment

The first perspective of temperature is the environment perspective as temperature is the guiding factor that directly determines the effects, positive and/or negative for all other environment factors in your garden.

  • Such as raising or lowering temperature can affect the humidity and the effect on the plant itself ranges from comfort level to affecting its daily biological functions (leaf to root pressure) to negatively impacting the plants development stage. 
  • Further still, temporary bad temperatures that cause stress can have reactions that enable a setting favorable for mold pathogens and other similar negative effects on the plant. 
    • If a plant is not healthy (nutritional) and fit (Brix levels) during stress times plants can become more attractive to pests and disease causing further problems.  :cute-little-worm-hi-and-bye-smiley-emoticon:

Understanding temperature and its effects on your environment and that upon your plants physiology and development will enable the gardener to transform temperature as a feared grow barrier to a hard to control force to being just another tool in the gardeners tool box and a simple factor to account for.


Garden Temperature Effect Formula:

Temperature & Environment (humidity) from canopy/middle/low fruit/media/root media level


_____Plant Physiology & Plant Development + Impact over time_____

= Garden Temperature Effect.



Genetic & Climate Tolerance

Plant type/strain/phenotype @ Climate Tolerance + Match Environment = Good plant Genetic

The Second perspective to temperature is from the plants perspective.  We tend to take the plant for granted that it will just automatically respond wonderfully to our specially designed environment.  However, before we can go that far with our expectations we need to ensure that we have the correct genetics, phenotype and sensitivity aspects accounted for that matches the garden environment or the garden environment adapted for. 

  • Hot and dry areas you want plants adapted for that climate.
  • Humid and hot areas you want plants adapted for that climate.
  • Account for known sensitivities or discard that genetic in favor of those who better adapt.

Regarding the type of plant environment think and research about the time of the season and how the plant would naturally and traditionally be grown.  We just want to match those conditions as best we can for the type of plant and the strain and phenotype. 

  • For example, spring environment for natural seedlings, early growth, pre fruit/flower, transition period, early flower, middle flower and end of flower/fruiting environments. 

The next part is to understand how temperature and relative humidity affects the plant.  By understanding this aspect you can gain the knowledge to control your environment as necessary and to optimum conditions if so desired.



Temperature, Humidity, Light Intensity, Spectrum and Plant Physiology

The key to optimizing lights in the environment is to control the heat.  We want to find the sweet spot that maximizes a lights intensity, spectrum and penetration with favorable conditions at all viable plant depths.  Either using one or multiple lights each light is treated the same way to determine optimum settings in terms of cooling and heating.


Light intensity & Environmental Formula

Temperature and humidity @ various plant levels + plants physiology = light intensity/quality


Often, If canopy temperatures are too high gardeners will often increase the distance between the plants and lights.  This directly affects light intensity and spectrum at depth due to light loss with increased bulb to plant distance. 

  • Air conditioning options.
  • Air cooled reflectors are options.
  • CO2 use.

This directly impacts the quality and yield of the plants lower fruits if lights are moved out the optimized distance.

  • Take light intensity into consideration no matter how close you are able to get light to your plants with cooling if you are able to get to close to a plant due to effective heat control. (light bleaching.)
    • Palm test - if too hot for your palm after a minute it is probably to hot.
    • Lumens -  
      • 50,000 to 20,000 lux is acceptable.


Temperature and humidity effects and damage can range from:

  • Reduced photosynthesis.
    • Leaf damage
      • Heat damage
        • High humidity shuts down plant process
          • negatively affects transpiration and stomata function.
        • Low humidity affects
          • Too dry air negatively affects transpiration rates
            • increased intake of water and nutrients
            • can lead to nutrient burn and other nutritional aspects
      • Light bleaching if too close
    • Lower light spectrum aspect if canopy is not maintained at good environment temperature/humidity.
      • Adjust light distance if applicable.
  • Media environment stress will alter the bio life of your media to potentially negative aspects.
  • Intersex plant trait potential due to stress depending on plant sensitivity and type.
  • Temperature and humidity can alter the media and the plants uptake and intensity levels of nutrients to dangerous levels.
    • This can affect temporary situations such as lock outs.
    • Can create longer term effects such as adding to soil/media acidification and creating a domino effects from causing locks to inviting

To visualize these effects in human comparisons think of a baby to teenager (seedling/cutting to veg) and/or an adult to elderly person (mid flower to harvest time frame) in harsh environments be it hot or cold this effect is dramatic on the younger people and older people (kids in cars and elderly people without air conditioning or heating as example) just as it does with young, elderly and sensitive people it is the same with most plants. 

  • This is why predators in the wild like old, the sick, the injured and the babies of their prey.  Easier meal as they are weaker.

This aspect is rarely appreciated by those who believe they understand temperature.  If you are after quality and yields, pay very close attention to your temperature levels doing your very best to not go into stress situations.  Just like "Goldilocks", plants like it just right.  Not to hot and not to cold.

  • You are also prepared to understanding on when to induce stress as applicable for your plant type. Be it to induce fruiting, sweetness or any pertinent factor for the plant being grown.
  • Some plants require stress factors to help them enter their next development stages.
    • Stable all the time is not necessarily as a good as matching the plant environment with its developmental stages.

Things to help manage stress:

  • When outdoors, encourage deeper root growth.
  • B-Vitamins before, during and after
  • High brix
  • CO2 use (PPM dependent)
  • Air conditioning
  • increased air flow/breeze above and through the plant.
  • If dry heat add some humidity depending on your plants needs at their development stage.
  • if humid head reduce humidity depending on your plants needs at their development stage.
  • Ensure reservoir water and watering in water is at a correct temperature.
    • Add ice bottles.
    • water chill system.
    • increase aeration when water temps rise.
      • lower oxygen content in warmer water.
      • low oxygen and warm water is good environment for root pathogens.
    • Add H2o2 to water periodically and 5 minutes before feeding to increase oxygen to water levels.
      • H202 breaks down into oxygen.
  • Ensure media temperature does not get out of proper range.
    • Smaller containers may be transplanted depending on stage of development of plants.
    • Larger containers soils should be shaded (if not already by plant).



Union Break!


I think this is how some might feel!



Garden Temperature Planning

During the planning stages of a garden the plan will often take into consideration the intensity, spectrum and over all the strength of a grow light in terms of yield and quality and work from the top down depending on what they can afford to purchase.  Generally people think they will be automatically able to place the light at optimum levels as stated in marketing for light quality, penetration and per suggested light distance from the plants but they do not appreciate their ambient and the entirety of the operating temperatures and the lights impact on temperature.

No matter what marketing says your garden temperatures will be determined along with other factors such as natural ambient temperatures and humidity and this directly affects the efficiency and overall quality of your lights in terms of heat, light intensity and spectrum in regards to the light penetration of the plants. 

Otherwise the scenario where gardeners purchase a high wattage light and cannot control the heat.  A very common situation that leads to the gardener raising their costs by adding in cooling options to make the situation more palatable to the plant.  The best answer is a reduced wattage light that equals the best operating temperature.

  • Having a 600w HPS or a 1000w HPS so high from the canopy due to heat that it is essentially a 400w light is not efficient use but this is fairly common, especially during summer months where budgets do not include effective additional cooling options.

Some people will consider LED lighting or other low temperature lighting in comparison to HPS or other high heat lighting and this is a valid option but I also recommend reviewing a smaller wattage light and in combination with another light for a better light spectrum. 

Which ever will give you better spectrum with good penetration taking into consideration the operational temperature of your garden. 

  • This is rarely the big light choice when the high wattage lights impact upon the garden is appreciated after taking into consideration impact the light brings to the operational garden heat as a whole and with other costs associated which typically lowers the lights efficiency in comparison to the other options. 

To plan out a garden environment we need to consider all the elements that make up the garden environment and affect temperature specifically.  Such as mechanical equipment and the natural ambient temperature so that we can determine cooling and/or heating requirements. 



How To Determine Heating and Cooling for Environment

Natural Ambient Area Temperatures - This is the normal temperature of the area you are going to grow in prior to starting.  We will use this in estimating operational temperature.

  • Day and night temperature at high and low temperature and humidity readings.
  • This information will determine if we need to add cooling or heating just to prepare or set the garden environment.
    • We will use this as our Natural Ambient Temperature


Natural Ambient Temperature Formula

Natural Ambient Temperatures (day and night) for operating seasons (intake air).


_____Estimated Heat (Lamps, fans, CO2 burners, insulation etc) @ BTU and/or Watts____

= Estimated Operational Temperatures per season as applicable

@ BTU and/or Watts for cooling and heating requirements



Now to determine the "Operational Garden Temperature" and then we can make adjustments to the build plan to obtain our environmental goals during the planning stages.


Operational  Temperatures: 

Intake temperature (outside/lung room air) needs @ BTU and/or Watts for HVAC


_____Grow room heat (Lights + other)_@ BTU and/or Watts for HVAC

= Operational Garden Temperature HVAC requirements

(Day and night highest and lowest temperatures per day for each change in intake air such as each season).




By adjusting the BTU/Watt requirements for the selected lights it can be estimated to an acceptable range of accuracy the impact that each light will have on the cooling or heating requirements for the garden.  As a general rule if the numbers are close I recommend going the light size lower or increase the BTU/watt requirements for additional cooling as to ensure better optimization for light penetration and spectrum.

Further additional BTU/Watt, cooling/heating consideration for:

  • Insulation properties of the room, ducting and any other pertinent factor.
  • Air conditioning, dehumidifiers, CO2 burners and ventilation are also factors to consider.
  • Add the wattage of heat generating aspects with the type of insulation and we can determine the cooling or heating requirements.



Grow tent 3x3x6 in a basement area that is consistent at 65℉= 18.3℃.  Should a 400w light require cooling.

  • We want to determine the cooling required for a 400watt HPS for a 3x3x6 size tent. 
    1. http://www.eyehortilux.com/education-room/btu-calculator.aspx
      • Enter 400w light wattage = 1365.200 BTU/HR
    2. http://www.calculator.net/btu-calculator.html
    3. Once the BTU needs match that of your light and combined needs of your room.
    4. Add the degrees needed to cool the light from your desired garden temperature.
    5. This is the temperature that can be estimated by your lights.
      • This will determine if cooling or heating or nothing is appropriate.
        • In this examples of a 400w HPS in a 3x3x6 tent with stable ambient temperature at 65f.
          • You will need 1,360 BTU/hour or 398 watt to cool this light by 20f to reach desired setting.
          • http://www.eyehortilux.com/education-room/btu-calculator.aspx
          • Since it will take similar BTU/watt requirements to cool that matches our light BTU/watt requirements at 20f we can determine the light will add approximately 20-25 degrees of heat to our ambient temperature.
          • Total heat is estimated to be in the 80℉= 26.6℃ to 85℉= 29.44444℃.
            • A  bit on the upper high side of acceptable.
            • Add air conditioning for better environment and less risk.
            • Add air cooled reflector.
            • Reduce to next light wattage option down/dimmer switch on light.
            • CO2 considerations due to plant temperature benefits if run on high side but may be more cost effective to consider cooling options.

Once all the BTU/wattage requirements are known and accounted for at depth of the plant for light intensity you can determine the entire cooling or heating needs by simply working your overall BTU/watt requirements as you did each light.  This will give you a good estimate on realistic garden environment and its requirements. 



Temperature in the Garden Summary

Once a gardener understands to an appreciation the perspectives and effects of temperature and how to control it the gardener can utilizes this knowledge to manage their crops effectively and expertly to the degree of control they build into their garden systems.





Humidity is water vapor in the air.  The amount of this water vapor (humidity) in the air we measure is in terms of relative humidity.  Humidity has a  significant impact upon plants both positive and negative depending on the percentage.  Often I see people who prescribe negative aspects of the garden plants to other reasons when in fact humidity played a role in their issue more so than what they prescribed as the culprit of the problem.  Many times this is in part an aspect for stretch and rooting aspects..

When humidity is in the correct "relative humidity" levels for a plants specific development stage it is the equal of what a perfect outdoor day feels like to us air and breeze wise.  The kind of day where you think you could just stay out on the porch, in the yard, have a grill as the day just changes your plans for you. 

This is what we want to create for the plants and it is not as hard as you would think.  Learning about humidity and how to effectively manage it is a key aspect of ones evolution in indoor gardening as we learn how to use the tools of advanced gardening.  I warmly welcome you to the tool shed.


Humidity aspects

  • Plants Transpire
    • This is how plants cool themselves, like sweating.
      • They release water into the air
      • But when the air is already saturated (high humidity)
      • The plant shuts down at a certain point.
        • This is why in part high humidity is dangerous.
        • when the plant cannot transpire is can become the equivalent of being bloated and this makes it easier for plants to become infected by mold and mildew infections as their is much more water inside the plant it is easier to infect.
          • Especially plants that are stretched due to high nitrogen and low calcium uptake.
            • Weak cell walls + full of water in plant = easy for mold spore to drill into and infect internal plant water and infection.


  • Seedlings and cuttings are most sensitive.
    • Think spring light and humid environment.
    • Cuttings may use dome in traditional clone rooting
    • Cuttings in air cloners do not require a dome
    • Seedlings require a dome only until they come up.
      • Careful adjusting from climate of seed tray to next area.
    • Placing a clear film over top of early rooting plants raises the humidity at plant level.
    • Putting a dry light blocking material around plants will help with humidity in the plant area.
    • Humidity of 80% is ok
      • We do not want to put pressure on roots at this point.


  • Vegetative growth a higher humidity of 60 to 70 percent is healthy. 
    • Gradually increase as plants develop.
      • Pay attention to leaves and adjust humidity up or down accordingly.
        • Generally this is controlled by exhaust, and/or air conditioning.


  • Flower around 40 to 50% is healthy.
    • To high humidity in flower is inviting to mold and mildew spores.
    • Air conditioning & heat as applicable is sometimes used to manage humidity.
    • A dehumidifier is sometimes used to manage humidity in flower
    • Be aware of the electrical needs and amp requirements of a dehumidifier.



Humidity Summary

For most the next big thing is in some bottle or in an up and coming light.  In truth, utilizing humidity as a tool will enable you control the plant in ways many do not yet effectively appreciate.  We see that a plant will grow about anywhere and this aspect has caused many of us to misunderstand what a good grow environment actually is and thus our expectations are not aligned correctly and we often sell our selves short by simply not understanding humidity levels.

Now that we understand humidity and growing we can better use it to our advantage to help control stretch and root growth, create environment conditions like early morning, mid afternoon, later afternoon and night for each stage.  As with other indoor gardening tools control of humidity is as complex or as simple as one wants it to be. 

  • I recommend optimizing humidity for each plant development stage with root growth, transplant and transition stages.


Very good video regarding humidity.


How to control humidity indoors

Good information on greenhouse and urban farming.  Their youtube channel: https://www.youtube.com/user/BrightAgrotechLLC/videos


Too Hot


Too Cold


Fan control


Air Conditioning


Air Intake, Filter, Inline Fan, Ducting and Air Cooled Reflector Hoods





Air Quality

Air Scrubbing

Air quality in grow rooms is dependent on several factors but most important for plants is co2, temperature, humidity and air flow.  However, we often do not think of the other aspects of air such as various particles such as pollen, hairs, dust, smoke, dander about anything than can float in the air. 

When considering I recommend a charcoal filter rated for the size of your room or slightly smaller than your rated CFM and run independently of any exhaust filter, Place the fan directly on top of the filter and secure to filter.  Allow fan to filter air blowing the air upwards. 

The higher position the filter the better but keep away from moisture and humidity of 80% or more as it will stop the effectiveness of your filters. 

  • This is operated in the garden and separate from the exhaust system or you can run dedicated air cleaning machines.
  • This will add some heat from the fan into the room
    • Account for additional electric needs.

To "scrub" the air take a filter for the size of your room or one with a lower CFM rating and do same with the size of the inline fan ensuring to match the correct size fan to filter. 


Aspects of air scrubbing:

  • Offers a higher degree of smell containment when used in conjunction with a traditional charcoal smell filtration system or any other effective smell management system.
  • Cleaner air in grow room.
  • Can remove gas created by end of life leaves which give off a gas that encourages ripening.
    • This is stated that it can be used to extend ripening times for some crops.
      • I personally would not consider as a base justification as I would tell you to remove the dead and decomposing leaves.
        • I do not necessarily believe this but it is stated in several competent writings.
  • Down side to blowing into the room is that it can distribute a fine charcoal dust from the filter.
    • A solution is use a lung room and scrub the air through that mechanism.
  • I do not find it normally necessary to scrub or clean grow room air but I find beneficial in following scenarios.
    • Consideration for high pollution areas.
    • Additional layer of smell protection when used together with other smell management systems.
    • Consideration for extra protection in breeding setups and will discuss such aspect in future breeding setup writings.


Video on Air Intake


A good example of the construction of a good air intake filter.


Ozone Air Scrubber Option

  • I do not recommend ozone for sealed or closed rooms as ozone is not healthy for plant life or most life in general.
    • Plants will negatively respond that is a exposed to ozone.
  • I have no problem with ozone being used for air filter system that is safely exhausted.


Carbon Filter (Smell)

  • Often carbon filters are used as part of the exhaust system.
  • Adjust for loss of CFM when determining fan size, approximately 25%
  • Replace approximately once per year.
    • Some filters you can switch the cap and extend the life cycle of the filter.
  • At 80% humidity carbon filters are no longer effective.


Carbon filter Video



Air Scrubber Summary

The quality of the air is something we generally take for granted as being a given.  It is not a necessity and adding more noise and heat to your garden area may not be the smartest move but it is an option that should be considered and ruled on as a matter of competence.  In my view, if you can do it, do it.  If you do, use it intelligently drawing and pushing the air in locations such as areas that receive little wind/breeze or are heat sink/spot areas as to distribute evenly throughout the room.

It also can offer an extra layer of smell protection when used in tandem with a tradition smell management system.  This option is also useful in areas of processing where extra filtration may temporarily be of value.  I do recommend to run filtered air in areas that processing takes place in.  This extra is more than a security measure it helps filter any animal hair, pollen or any matter that may be undesirable and visible under a microscope.  For example, when a dispensary is analyzing your crop.  Well filtered air is a blessing in preventing embarrassing detritus in the crops.

Regardless of ones view of this, it is a tool that can easily be employed and should be considered and ruled any time an applicable scenario presents itself for its use.




Carbon Dioxide or C02

Carbon Dioxide is one of those tricky subjects that is easy to misunderstand.  Generally, CO2 is a great a marketing aspect for indoor garden suppliers but what is not often said is how to effectively use them.  I believe many gardeners misuse or they are not efficiently using CO2.  In the end this cost money and is wasted resources.

When using CO2 it is best to be used with "best practice" along with "best practice" in lighting, nutrition and management.  Then the capabilities of achieving the most from your genetics become a possibility.  If not done to effective levels of competence with all other aspects of the plant the reality of the benefit of CO2 is greatly diminished.  Thus, CO2 is only a viable option for flowering for those with well constructed rooms as to maintain efficiency levels in particular in reference to financial costs.

However, it is beneficial to add higher levels of C02 in early veg, cloning stages as the required PPM is far less and this can assist with maintaining heat and light tolerance. 

  • This can be beneficial preparation in the stages before hardening rooted plants off outside or for other needs.
  • Can be a benefit when you ship clones to help them endure shipping as they are stronger.

High Concentrations of CO2 is bad for people and animals and can kill when it reaches 1% of the air.

  • Gardens use approximately 0.15% of the air.
  • However, use a CO2 meter to ensure that no malfunction of a burner and compressed tank could cause a disaster.
    • never saw nor heard of this happening but lets not be a first.


Using CO2

  • CO2 is heavier than air.
    • Thus we put CO2 so that it falls or "rains" CO2 down on the plants.
    • Evenly distributed
      • Small fans strategically pointed upward can keep CO2 in air and over plants and helping distribution.


  • "Best Practice" is to have the grow rooms at optimum levels of C02 during the day.
    • Often CO2 is run in closed rooms.
    • Often 15 minutes co2 dose and then 15 minute air exchange and repeated throughout day cycle.
      • With this setup you often run air cooled lights.
        • Exceptions can be with lung rooms and recirculated air system.
          • This is a trade off in cost efficiency where you run the CO2 at optimum levels throughout the day and replenish as your plants use.  Often used in conjunction with a CO2 Meter/controller.
        • Their is no benefit to running C02 during the night/dark period.
          • Will turn your plants yellow.


  • Seedling, Cloning, initial transplant cycles you only need 300-500 ppm.
    • Few leafs and little photosynthesis.
    • Raising temperature at this level will not help
      • CO2 at this level will assist with plant tolerance to heat and light stress.


  • Vegetative stages after rooting increase CO2 to 500-700 ppm.
    • As plants increase in leaf and growth they will use more energy/photosynthesis and sugars are made.
      • Adjust/Rise the CO2 levels accordingly.
        • It is not harmful to the plants if PPM's are higher than normal for period.
          • This increases the cost of your grow to have ineffective CO2 ppm amounts.
          • Do not raise temperature in vegetative area as in later flowering period.
            • The plants can become more hardier to withstand light intensity and higher temperatures.
              • Is generally part of a CO2 garden operation to treat at this stage as to prepare for the higher temperature and more intense light in a flowering/blooming or an outdoor environment.
                • Helps reduce shock in this regard.


  • Flowering stage keep CO2 at 700-1050 ppm.
    • Increased growth and bud production by running CO2 during the first 1-5 weeks of flowering.
      • Once flowering has truly begun CO2 may or may not be effective.
        • Their are strong views for and against continue or discontinue CO2 at this time of development.
          • Traditional CO2 use would finish 2 weeks before harvest approximately.
            • I have no direct experience with CO2 in terms of comparison as above.
    • Raise temperature 85f (30°C) to 95f (35°C) for full benefit of CO2.
      • Watch for heat stress in plant and adjust temperature accordingly.
      • You potentially lower your lights towards the canopy if desired paying attention to light bleaching aspects.
        • Maximizing your light source but just above the bleaching zone and before the plant shows stress is your optimum height from canopy to light.
          • Pay attention to height of plant, co2, temperature and humidity levels.  Manage adjustments to remain in that range.
            • Plants become more light tolerant with higher CO2 PPM and higher temperature.
              • Helps reduce shock in this regard and allows for leafs to function at brighter and hotter temperatures than normal.


  • Examples of Setups with Enough Light for CO2 Injection up to 1050 PPM
    • I like full spectrum light in addition to brightness, traditionally they go by brightness.
      • 3' x 3' space - 600W HPS or HPS/MH Combo or LED/full spectrum & bright
      • 3.5' x 3.5' space - 2 x 400W HPS or HPS/MH Combo or LED/full spectrum & bright
      • 4' x 4' space - 1000W HPS or HPS/MH Combo or LED/full spectrum & bright



CO2 Garden Options

CO2 Generators and Compressed CO2 are the most effective and efficient ways to add CO2 to your garden area especially for flowering areas.  Vegetative areas also benefit but a due to the less amounts needed this can be actually achieved by other means than generators and compressed tanks. 

It is possible to use fermentation kits and CO2 bags purchased from a store, however this is costly.  If you are seriously into making wine you can also do this if fermentation concentrations are sufficient, smaller areas.  Also for those who live on a farm and/or those who make ethanol, the fermentation process releases CO2.


CO2 Generators & Compressed CO2

  • CO2 Generators often run on propane or natural gas.
    • Some generators are optimized for higher elevations
  • Compressed CO2 is run with a regulator and bottle setup.
    • Costly operationally
    • I like best for:
      • When needing fast increases of CO2.
        • Bug infestation.
        • Management option.
    • When testing CO2 in your environment before dedicating to it.
      • Low initial cost and is often consideration for a "trial" run to evaluate before dedicating to a burner system which may require some room alterations.
        • In some garden situations I like burner systems and the use of a CO2 tank in certain situations.
          • Tank being largely used in supplemental aspects and certain situations.



Very good informative video



AGF-l7_h2xjHO4KHTHdjSmPagnXgvKYwpRtGUVQSLex Blazer



CO2 Burner Information, Not an endorsement, for illustration purposes.  I have no opinion on quality.


Set up for this style of burner to give illustration of setup understanding.



CO2 Summary

CO2 use is ideal for most growers only in vegetative stages due to the low PPM requirements and benefits in preparing the plants for follow up stages.  Often smaller gardens will use a bucket or bag CO2 product and hang high as CO2 is heavy and will fall.  Fans pointed up will help keep CO2 in air column.  The costs of these products can be high and some home brewers may be able to devise a system to take advantage but for most this aspect is a pain the ass.

CO2 compressed tanks are a better alternative to the bags due to the low PPM in veg the cost efficiency of tank is more attractive and bags and buckets take up space and are generally a pain the ass.  I recommend only for trial purposes.

Dedicated gardeners with closed systems can create systems that take full advantage of the CO2 and to do this requires a degree of best practice aspects all around.  The average gardener can not easily achieve this no matter what marketing says.

Additionally their is much debate with merit on both sides for and against continued CO2 use after flowering/fruiting has begun.  I have no experience with this aspect and will update as more information becomes relevant.






Ventilation is a big part of creating and managing the entire environment.  First we need to understand the needs of the plants being grown.  A wise gardener can not only create a stable grow environment but can manage with accuracy the environment in regards to temperature, humidity, CO2 and air quality.  Their are a variety of setup and options that offers a range of  capabilities depending on a gardens needs. 

  • Understanding how to use these tools is vital in creating optimized grow areas.  What ventilation tool works in one setup may not be ideal in another ventilation setup. 
    • For example, dealing with humidity is different in a tropical area compared to dry climate area. 

Often people will be told that one method may not be good when in fact that method may be most beneficial in certain situations.  This aspect negatively works against us by instilling these misunderstood views.  Creating an effect that limits the typical ill informed gardener in knowledge and capability in respect to options to utilize to manage their garden. 

  • This may in part be due to much of the communities knowledge coming from marketed directions and forums, never mind this one :33zzold:



Ventilation Types

  • Active or Passive Ventilation.
    • Active Ventilation - Using a slightly smaller inline fan to intake fresh air into your grow room.
      • This has less strain on your garden's extraction fan and is more efficient.
        • Exhaust fan typically will have a filter attached
          • This reduced effectiveness of the fan.
            • Making it sensible for a lower intake fan.
            • Using fans with control switches can give you better control.
      • I tend to recommend that if a grower can afford and if they plan to expand at a later date to over spec the requirements using a speed controller for the fan to adjust to correct CFM rate for the grow.
        • For tents
          • I do not recommend a weaker intake fan rated CFM for tent size as negative pressure is a problem on stitching.
        • I do not recommend an overly strong intake fan rated significantly higher than your CFM needs as a whole. 
          • Consider for intake fan, the next fan size or model down from your intake fan. 
            • Adjust for exhaust filter and ducting losses.
              • Intake is 8 inch fan with dimmer switch and an 8 inch exhaust fan with/without dimmer switch.
              • Intake is 6 inch fan with a 8 inch exhaust fan.
              • Intake is 4 inch fan with a 6 inch exhaust fan.
      • Negative of too much ventilation is high heat, high humidity and low levels of CO2, this will negatively affect photosynthesis.
      • Negative of too little ventilation is low humidity and stomata/transpiration issues.
        • Illustrates traits often associated with genetic aspect when in fact it is a result of a plant responding to environmental stress that the gardener may or may not appreciate.
        • Extreme situations of low humidity will put the plant in a hibernation or pause state until the environmental stress passes (humidity levels return to functional levels).
          • Dry climate areas with low humidity are higher risk.


  • Passive ventilation - I dislike this typically due to the following.
    • Basically is a low vent on one side and a high vent on the opposite side of the room or tent.
    • Works best during colder periods when the difference between inside and outside temperatures is greatest.
      • Passive ventilation used alone can’t extract humidity.


Union Break!


I think this is how some might feel!


Determining Ventilation Requirements

  • Cubic Foot per Minute of ventilation requirement is needed.
    • Exchange your garden's air at least once per minute at minimum.
      • Not as important in vegetative growth when plants are small as they have less leaves.
      • "Best Practice" is to exchange once per minute.
        • Ensure fresh air intakes are managed (intake filter) for bugs and pest that could enter the garden via this pathway.
          • Intake filter will reduce approximately CFM's by 25%
          • Bends in ducting reduce CFM's drastically.
            • Ducting curved 30 degrees reduces CFMs by 15%
          • Air quality - Low humidity intake air will need less ventilation until humidity is correct as the leaves will begin lose moisture and negatively affect the stomata and the photosynthesis process.


  • To calculate initial cubic feet per minute of ventilation you need, start with calculating the size of the garden in cubic feet. You do this by multiplying the height, length, and width of the room.  



Ventilation Summary

Understanding ventilation and how to use it in various situations is a skill that few appreciate and with automation capabilities it becomes rarer still.  Often their are negative garden issues associated with to little ventilation within a multi ventilation setup and when this occurs it can lead to potential harmful situations like mold or heat aspects.  It is important to understand ventilation but one can make it as complex or as  simple as they wish.  The point is that now one can make an informed decision and have some direction on how to effectively setup for each perspective gardeners needs.




Environment the Tool and some tools

The environment is the driving factor in a garden and as such it is wise to utilize this to our advantage rather than to just build around it.  As an example, this is a common practice done by to instigating the flowering stage by adjusting the timing of the lights to further adjustments in temperature and humidity depending on how simple or as complex the design of the garden and needs of the crop are.

Understanding how to use the tools such as ventilation and the different setups that enable various capabilities that may offer solutions to gardeners with certain situations and/or needs.  Further still this knowledge gives you the capability to adjust to environmental conditions experienced out of normal weather patterns. 

  • The key is to appreciate that assisting a plant through a stressful period of time be it normal growth period development and/or environmental based stress that addressing the plant at all levels from environmental aspects to nutritional aspects as to ensure the overall health of the plants is strong. 
  • A gardener must not depend on the strength of any one aspect to cover for not being competent in other areas of plant care such as heat control but not humidity and also take into consideration nutritional and plant physiology aspects for before during and after the stress event.


Some environmental control aspects.

  • Hot and Cold areas
    • Sealed Room Consideration (higher electrical cost but is easier to control grow environment)
      • Air conditioning aspects
        • Air conditioning
        • Air cooled reflector hoods
          • Insulated ducting
      • Carbon dioxide
        • Burner.
        • Bottled.
        • Bucket/Bag grow shop kits
        • Wine/Ethanol making.
      • Air Filters
        • Pest control
        • Air quality and smell controls.
      • When seasonal outdoor temperatures are not good.
        • Air intake from inside the building offers stable temperatures and humidity levels.
          • Use an Lung room or tent to temper and treat air before going into garden area.
            • Hot areas
              • Outside air intake into an active cooling lung room.
                • Balance for proper humidity level and temperature.
            • Cold areas intake into an lung room.
              • Outside air intake into lung room.
              • Grow room exhaust into lung room
                • lower temperature and exhaust or intake into grow room as best for your setup.
                  • If exhaust to outside this helps remove aspects of ice build up.
                  • If exhaust to grow room ensure proper temperature and humidity levels for current growth cycle.
          • Lung room option 2
            • Intake air from inside building to lung room (stabilized but not ideal)
            • Cool or heat lung room and obtain proper humidity level
            • Exhaust lung room into grow area.
            • Exhaust grow area outside (filtered most often)
              • Exhaust grow area inside of building (Use the heat) or
              • Exhaust grow area to a lung room for temper for outside temperatures.

The biggest thing is to make informed and calculated decisions when working an issue.  Their is no need to panic and rush into a decision that make things worse.  Gain control of the situation and sit back and look at it through eyes as if you was going to give advice to another.  Try to see the garden as if for the first time and go over your grow history and analyze.  The answer or the answers are their.

When you can during stressful climate times and periods, go for nature walks and see what plants are doing well and see if get any ideas! 


Video on Heat in the grow room


Video on cold in the grow room


Fan controller video


AC video


Air Cooled Hoods & Ducting Video


Filter size video


Additonal tools


  • Click Hortilux logo for Watts/lights to BTU calculator
  • A BTU, also known as a British Thermal Unit, is a measurement of the energy needed to cool a substance. Grow lamps generate a lot of heat. By converting your wattage into BTU per hour, you’ll have the information you need to keep your plants cooled so that they don’t burn up from the heat of the grow lamps.
  • A BTU is also the equivalent of 252 heat calories, not to be confused with the kilo-calories of food, and of approximately a third of a watt of electrical power. When speaking of cooling power, the BTU also works in reverse.
  • The air-cooling power of an air conditioning system refers to the amount of thermal energy removed from an area. Hence a 65,000 BTU heater and a 65,000 BTU air conditioner are of roughly the same capacity and size. The higher the BTU output, the more powerful the heating or cooling system.
  • The thermal energy needed to raise water one degree Fahrenheit can depend on the original temperature and the method used for heating. Therefore, it is possible to get several different definitions of a BTU from different sources. This rarely has a palpable effect on consumer product information, however.


Click for Phresh CFM, Cubic Feet per Minute Calculator


Click for Phresh CFM Calculator



Indoor Garden Environment Summary

Ok, by controlling the environment we can affect plant physiology and development stages but as we know their is no simple "one size fits all" formula for managing the indoor garden. 

By understanding to appreciation the aspects discussed in this writing you have created a base of knowledge that will allow to address virtually all the varied aspects of the environment and how to control them to serve the plants and you very well.  By making a true home for our plants, they will truly it make it that and live their life healthy and fit.

  • Always understand via competent analysis of established to new technology that can affect indoor environments.
  • Continue to learn on plant physiology.  Always be the student.
  • Continue to learn on plant and environment interactions and aspects.  Always be the student.

It is not so important that any specific method be strictly followed as that you have a true understanding of all things affected and then from that knowledge you apply effective methods to obtain the conditions you want. 



For You





When environmental and plant physiology wisdom is effectively gained it can become the advantage that can equal or best the long established or it can just be what makes a garden happy and productive. 

~JJ The Gardener



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