Designing your own grow room


What's a sealed room?

Simply put, it's a grow room where there are no vents to the outside and the entire environment is controlled from within the room. This approach to cultivating opens the possibility of providing your plants with the perfect environment where the temperature and humidity can be controlled to a 'T' and headaches such as odor and powdery mildew can be properly controlled. A sealed room can also provide any business-minded individual the ability to form a dynamic foundation in which their business can scale quickly and efficiently.

The Business Side of Proper Cooling-- Extract from Rosebud Magazine, June 2010

Much like any business, it's all about planning, cash flow, and ROI (Return On Investment). These 3 key points can turn any hobbyist with a green thumb into a highly successful enterprise.

The business side of planning your sealed grow room

Planning sounds fairly easy and perhaps even boring but it can be quite inspiring and provide you with the confidence to move onward and upward. The first phase of planning requires some thought into where you would ultimately like to end up. What would the ideal situation be, how many lights, total yearly yields, and obviously, total revenue? Once you have the ideal situation drawn out in your mind, the next step is to connect the dots on how you will go from start to finish. You must think about the size of your setup, how many total square feet or what type of power would be required? These questions will dictate and bring clarity as to where you can setup a facility in your area. As you dig deeper into planning you'll start to formulate a rough budget, I say rough because most people dream big and that's OK just keep in mind you may need to start a bit smaller and scale up over time. It's important to start broad in your planning to get an overall snapshot of where you're going. As you progress through the planning stages your thoughts should start to get more detailed to the point where you have accounted for almost everything. By even writing a few ideas down you'll be able to focus on critical elements and become confident that your plan is in motion.

The proper cooling side of planning

Planning the cooling in your room is critical as it will dictate what's possible within your growing space and whether or not you'll be able to provide your plants with the perfect environment. Some questions to ask when planning would be; what are the hottest summertime temperatures outdoors and if you could have the perfect room indoors what would the temperature and humidity be set to? By answering these two basic questions you'll be left with only a couple products to select from.

There's a handful of ways to cool your room; venting, air cooled hoods, water chilled lights/fans as well as water/air cooled air conditioning.

Venting to the outdoors is the cheapest way to remove heat from your room. A major drawback to choosing to go vented is that your room becomes susceptible to whatever mother-nature will throw your way. Meaning, if it's wet outside, your room's humidity will spike, and if it's hot outside it could become an inferno inside. The next method of cooling is a hybrid style of ventilating using air-cooled hoods. This setup works by running a duct from the outdoors which is connected with inline fans to your lighting hoods thereby blowing the heat from the hoods to the outdoors. It's a great way to keep your room completely sealed as well as using less electricity. Room temperatures will be constrained by the outdoor temperatures and there's a fair amount of equipment that's required to make everything work cohesively. Next on the list of ways to cool is water chilled lights and/or fans. This method is made possible by constantly chilling a large reservoir of water and passing the water past bulbs and/or fans, removing heat directly from the source. A benefit to using this method is that it allows for more precise cooling, as you will size your chillers compressor to the overall heat load of the room. A drawback to going this route is that this method will not resolve any humidity issues in your room as the air in the environment is never conditioned. Lastly, the most accurate way to control temperature and in most cases humidity is through water or air-cooled air conditioning. These systems have evolved over the years from requiring mechanics on site to the invention of easy "do it yourself" systems. These systems have several benefits: the larger units are designed for commercial applications, meaning they're able to run 365 days a year, giving you ultimate control of your room. Benefits such as programmable thermostats, dual room damper packages, and various other environmental management additions can be easily implemented at any time. Drawbacks to air or water cooled air conditioning include: a sizable upfront investment and overall power consumption which can also play a factor.


We've all heard the phrase: "cash is king" and it's completely true! Cash-flow is king! Cash-flow is money being generated from the business on a consistent basis and it's the lifeline of any business. The constant flow of cash is used to pay any overheads or bills in order to keep the business running on daily basis. Like many things in life, everything seems to operate much more smoothly when there's less friction or stress to slow it down, and for business that means we want to make sure there's no lack of funding for your enterprise. The easiest way to do this is to make sure you have predictable funds being generated to allow all of those bills to be paid. One way to do this would be to split up your crops cycles so that they're staggered by a month or two. This will allow you to pay the bills and take a little bit for yourself to keep you going until you build up a regular budget that can sustain itself. It may seem very basic but it's the single largest mistake any start-up business runs into. By nature, humans have a hard time saving and this approach ensures that when that rainy day comes around, and at some point it always seems to in this business, you'll be prepared.

Cash flow using proper cooling

Having your room dialed into the perfect temperatures will relieve a lot of every day headaches that come along with running your enterprise. By maintaining an optimal environment you can then focus on a few key strategies to running a successful room. Keys such as: the ability to enrich your room with CO2, keep mold and powdery mildew at bay and allow a proper foundation for controlled experimenting of nutrients, lights and any other changes you would like to make. A fully controlled environment will provide you with continuous yields that you can depend on, providing you with exact feeding, spraying and cropping schedules. Best of all you'll remove large swings in yields allowing the easy budgeting of your business, making sure no bills are left unpaid and it's just 'business as usual.'

Return On Investment (ROI)

ROI is a fancy saying that's used far more often than it's understood. ROI is best used when comparing investments in your business. It's very easy to spend money on specific factors and for the most part they are all good choices, however, no one's budget is unlimited. This presents tremendous opportunity to really zero in on what will boost the company's profits by focusing on improving one or two major elements of your setup vs. handfuls of mediocre improvements. Tracking the return on investment allows the person running the business to compare the dollars spent on different parts of their enterprise and understand where funds are best spent to grow their bottom line. The best way to look at any ROI decision is not to focus solely on the initial cost of a particular investment, but rather what it would cost your company in the long run if you chose not to make that investment.

Investing where it counts

There are unlimited places to invest in your business, and to find out where you'll get the largest return on investment you'll have to weigh the pros and cons of many important elements within your room. Cooling is by far one of the most important aspects of any room. There are many levels, in terms of dollar value, in which you can invest and most of the decisions will be dictated by your budget. Many experienced growers have planned their rooms around environmental control and have been wildly profitable. Specifically, in setups of 6-lights or more, a significant investment into both air conditioning and a sealed room will pay for itself many times over along with removing many headaches that plague the majority of grow rooms. At the end of the day, it's about making your money work for you, as there are only so many hours in a day. Why not make it easier to run your business so you have more time to enjoy the rewards of your hard work? Hopefully, after reading this article you will be able to investigate the methods of running any successful business and how properly cooling your environment will provide you with countless quality yields and reduce many everyday issues within your room.


The summertime season: Heat & running an indoor garden...

Even though summer is still a few weeks away, most of North America is seeing some pretty high temperatures. This is great on the leisure side of things but it's starting to wreak havoc on many grow rooms. Even venting the lights to the outdoors is becoming an issue because the outdoor temperature isn't cool enough to remove enough heat. The best way to beat the heat is by making sure you insulate your rooms' walls and ceiling with R12 insulation or better. You can find both the styrofoam board and fiberglass insulation at most hardware stores. The next step would be to make sure you seal up any possible holes leading outside of your room (i.e. to the outdoors, to adjacent rooms, the ceiling, etc,). Usually spray foam is the easiest method as it can easily cover hard to reach places and will harden and seal quite fast. The reason for plugging any holes is that once you add some form of cooling to the space you don't want any leakage or outside influences messing with your temperatures. Next, you're going to have to choose from a variety of cooling options depending on your setup. For smaller setups, a small window or stand-up air conditioner may be OK, but for any mid-size to large setups some form of split air conditioning or water chilled equipment would offer the greatest overall temperature control. The latter is definitely a hefty investment but then again what would it cost you to shut your room down for the summer?

The blame game

It would seem that even though technology and innovation have continued to evolve, human perception has not. As humans, we generally believe that if something goes wrong it must have been due to someone or something else messing things up. Unfortunately, there must be a level of ownership and responsibility as we all have choices and learn from experience whether good or bad. What am I getting to? I hear all too often about an individual’s crop failure and how it’s everyone else’s fault besides his or her own. “The nutrients ruined it. They should have told me” or “my dehumidifier broke, it’s raining in my room and now I’ve got mildew, this product sucks!” Usually, I ask these people if they changed anything out of the norm or if they had any fail-safe options in place? Most times these ideas were implemented on the fly and poorly thought through (or just plain lazy) all of which were entirely down to their own poor decisions. Given the number of amazing products available today for growers of all levels, it can be quite overwhelming trying to zero in and focus on key aspects of your sealed room. Well, guess what? To some degree, they’re all important and that’s why planning is a necessity. Once you have a plan in place, stick with it and don’t deviate. Planning will build the foundation and take the guessing work out of it. Plan for everything! A few must have’s in any sealed room should be as follows:

A safe room:

This means everything from room structure to plumbing and especially electrical safety, do it right the first time and don’t patch things together because it will come back to bite you. We’ve all cut corners and said “that’s good enough” and sure enough it always becomes a problem. Like any problem, they can all be overcome but I’m sure you’ll agree if we can avoid very serious problems such as floods and fires we’d be in a much happier place.

The 'no brainers':

Things that just make plain sense and are quite easy to do. Top on the list is a high-temperature cutout; some way or strategy to shut all and/or most of the power quickly, especially your main lights if the temperature strays above 90F. This way you’ll avoid crop failures and most importantly protect not only your plants but also your beautiful room. This will have little effect on your plants and will protect your investment. Another no brainer is tools that allow you to do your job more easily. If you need a hose that’s 20 feet then don’t buy a 15-foot hose because it’s on sale. Also, instead of being hunched over breaking your back working in a dimly lit corner, get a proper table of the proper height where you can feel much more relaxed and install a basic light so you can do your job better and more efficiently. They don’t seem like big deals but do make a world of difference in the end game.

Be responsible

Take ownership in your room, that way you can stop blaming other people for your misfortunes and be proud of the successes as well. If there’s a problem, find a solution and fix it. Nobody gets ahead in life by complaining and blaming, it’s a waste of time so why do it? Try to align yourself with likeminded people: others who are trying to achieve similar goals, as two heads are always better than one. Keep to your master plan: through new experiences, your knowledge will grow and so will your yields. In the end, as long as you’re giving 100% at becoming the best you can that’s all anyone can ask. Take ownership in what you do and during those tough times (they’ll always be some tough times) try not to blame others or feel like someone owes you because you chose not to be prepared.

Don't wait until it's too late...

The heat is on... Unfortunately, most growers wait until it's too late to solve issues within their garden. Many just settle with mediocre results and the constant curveballs mother-nature seems to throw at them. With summertime now being in full swing, it means scorching hot temperatures in your room. It's at this point where you must take your room to the next level and give both yourself and your business the proper tools to maintain consistent harvests no matter what time of year. You need to convert to a sealed room.

The concept of a sealed room is quite basic; a sealed room is a growing environment where there are no holes or air exchanges to the outdoors or any other room. It doesn't need to be airtight, however, the closer to airtight the better. A sealed room is really no different than your room right now, however R12 insulation or better should be implemented in the walls and ceiling and any holes or large cracks should be filled with expanding foam to help keep everything in (or out). Once everything has been sealed up, we can start to introduce great products to help push your next crop to a whole new level. Products such as: air conditioning, carbon dioxide (CO2), ultra-violet (UV), air purification and odor removal systems.

Air conditioning will be one of the most important first steps in a sealed room as it's really the only way to control the constant heat generated by all those lights. Air conditioning will provide your environment with the balanced temperatures that plants thrive on, and as a bonus, substantially drop the humidity in your room. Many air conditioners will allow for both day and night temperature settings along with additional capabilities such as: the addition of electric heaters inline for locations where winter and/or nighttime temperatures drop too low. In recent years a handful of companies have offered "do it yourself" systems for all room sizes, making installation quick and efficient requiring only a wrench, a screwdriver and a few hours of your time. One of the additional benefits of having air conditioning is the ability to use the large 2000CFM (cubic feet per minute) indoor air handler/blower. This blower mixes CO2 thoroughly throughout the room and can be used to push the entire volume of air past a UV air purifier that's placed within the ducting, killing all bacteria and spores as well as helping to eliminate powdery mildew.

Once the sealed room has been established and you have your temperatures under control the next step is to introduce CO2 into your environment. In many cases, CO2 can bump yields as much as 30% and because you won't have cracks or air leakage all the CO2 will stay inside the room and your plants will love it. Plants use carbon dioxide during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. The best way to ensure precise levels is by using a digital CO2 controller with a built-in sensor, allowing you to set exact PPM (parts per million) dependent upon your schedule.

After providing your plants with the best possible environment to grow top quality product it's time to deal with smell and air filtration. This can be done in a variety of ways: there are many manufacturers that produce high-quality air filtration systems. The easiest way to stop dust in the air and eliminate any odors is to find a system that provides an all-in-one solution. A system equipped with a pre-filter to collect any dust and dirt, a large surface area of charcoal to scrub the room of any odor and a large blower fan to circulate the total volume of air in the room. It's important that the fan is large enough to accommodate any the restriction that the pre-filters and charcoal will impress on the fan. If anything, eliminating any harsh smells will provide you with peace of mind.

In the end whether for pleasure or profit a sealed room is the next level for any indoor gardener looking for the ultimate in efficiency and maximizing their yield! These handfuls of techniques are made possible through the sealed room concept and it's really just the beginning as having a perfect environment will open the doors to many breakthrough strategies in lighting, nutrients and environmental control. Never stop learning and always strive for greater things as the rewards of your hard work will pay dividends time and time again.

Humidity and indoor grow rooms

Indoor gardening is following the course of most emergent industries in that solutions borrowed from mature industries are adapted to suit. Over time plant products that originated outdoors such as: filters, fans, building supplies, and lighting technologies have all been adapted to better fit the needs of the indoor gardener. As the marketplace continues to develop, information about product performance continually passes among growers, retailers, and manufacturers. This shared information eventually leads to improved products that result in better, and more efficient, growth techniques.

Rapid changes may occur as an industry moves towards maturity and gaps in knowledge can be common as users strive to keep up to date with new tools, supplies, and equipment, while manufacturers get caught up in development and do not take time to communicate with the end user. Thankfully, there are industry publications to provide a bridge.

Thanks to information published over the past several years, indoor growers have become aware that too much humidity can cause disease, rot, mold, and mildew and that this is especially true when plants get to be dense and full. However, what solutions work best and why, or even how much moisture needs to be removed from a grow-room, are areas in which awareness isn’t as common. This article addresses humidity controls in grow-rooms.

Humidity and grow-rooms

What is the difference between humidity and relative humidity?

Rule #1: Relative humidity (RH) is not the same as absolute humidity

Absolute humidity is the quantity of moisture in the air—for example 100 pints of moisture in a grow room—whereas relative humidity refers to the amount of moisture in the air relative to the maximum amount of moisture that could be in the air (75% relative humidity = 75% of the maximum moisture content).

Rule #2: A warm environment can support more water vapor than a cool environment

An 80°F room can have twice the moisture in it as the same room at 60°F. In other words, a room that is 80°F and 50% RH during the lights-on cycle can reach 100% RH if the temperature drops to 60°F. When relative humidity reaches 100%, this is called the 'dew point'. As the temperature drops, liquid water, or dew, will quickly condense out of the vapor. Adding a small heater to raise the temperature by several degrees in an otherwise cool but wet grow-room is a simple way to reduce the percentage of relative humidity when the lights are off and can be a useful stop-gap measure while working on a longer-term solution.

Rule #3: Your key to mold control is moisture control

Mold growth requires fungal spores, organic material, and moisture. Spores are ubiquitous and difficult to remove through filtration, so moisture is the only variable you can realistically control. The idea is to solve any moisture problems before they become mold problems. Experts consistently agree that 50% relative humidity or lower is your target for preventing mold.

Rule #4: Humidity equalizes rapidly

While temperature stratifies and requires air movement to achieve balance, humidity equalizes rapidly. This is useful because it means dehumidifiers don’t require ductwork in most grow-rooms. Rapid vapor equalization also poses a challenge, because water evaporates quickly, forcing growers to reduce evaporation by cutting unnecessary water exposure to open air.

What are my options to control humidity?


Ventilation is best for small grow rooms and can work well for most hobbyists. This solution works by diluting the water vapor, which works well in dry climates with moderate temperatures year round but comes up short during humid seasons or in humid climates. An example of using ventilation to keep a grow room dry is when the conditions outside of the room are controlled by the use of a grow tent. Growers using this method should filter the incoming air with pleated air filters to help prevent the introduction of pests and other air-borne contaminants. One major issue with using ventilation is that it does not work well for growers using supplemental CO2. Another downside to ventilation is that it will have some effect on room temperature. Though outside air in New Mexico or Arizona is very dry, it can be extremely hot or cold at different times of the day, providing less than optimal results at those times.

Air conditioning

Air conditioning works well at removing moisture when the lights are on, temperatures are near 80°F and there is a need for cooling. Using an air conditioner to dry a room when the lights are off is not recommended. Excessively cold temperatures can stress plants. While air conditioners use great amounts of energy to remove moisture and as temperatures go below 70°F, air conditioners tend to freeze up. Supplemental heat can be used to drive the need for cooling and to prevent the air from getting excessively cold and freezing up the air conditioner. The problem with this is that supplemental heat requires lots of energy and quickly becomes expensive to maintain. It isn’t wise to use your cooling system as a long-term moisture management solution.


Dehumidifiers are the only sure way of controlling humidity at all times. Although commonly available dehumidifiers are designed for light use in residential basements, there are two companies in the United States that build high-quality, high-capacity commercial grade dehumidifiers. These are extremely energy efficient, don’t create excessive heat and will last for many years. For smaller grow rooms, removing the condensation bucket and attaching a garden hose to drain the water (if needed) is enough to modify basement- style dehumidifiers. Larger operations will want to consider the extended reliability and moisture removal capacity of commercial-grade dehumidifiers. Also, for best performance, install air conditioner vents and dehumidifiers as high in the room as possible to ensure that cold or hot air is not blown directly on plants. This will assist with water drainage from the equipment as well.

How much moisture does my air conditioner remove?

With so many variables in play, there is no general rule of thumb to estimate moisture removal based on air conditioner model, brand, air temperature, run time or room size. Fortunately, there is a relatively easy method any grower can use to find out how much moisture their air conditioner removes.

Collecting runoff from the air conditioner is usually a fairly simple task. Water from a 24-hour period is sufficient for finding your water removal rate, but the longer time period, the better. Yet, collecting water over a four-hour period—with air conditioning running, of course—is enough to estimate the amount of moisture your air conditioner would remove in 24 hours. Conduct this experiment during a time when moisture is most problematic, such as when plants are large and the external environment is humid.

Don’t forget that air conditioners often don’t run continuously when the lights are off. In other words, if the air conditioner runs constantly when the lights are on, but only for, say, 30 minutes when the lights turn off, your air conditioner isn’t removing any water for a major portion of the cycle.

How much moisture needs to be removed to protect my plants?

Plants transpire about 99% of the water they receive, so the amount of water your plants receive is approximately the amount that needs to be removed each day. For example, 30 plants each receiving 0.5 gallons per day equals 15 gallons of total water per day. If you water every other day, divide by two to get an average per day.

So, 8 pints per gallon multiplied by 15 gallons is 120 pints per day of moisture into the room. Use the results of your moisture collection experiment to subtract whatever water your air conditioner removes from your total input water. If you have any remains, then that is the water that must be removed by a dehumidifier. It just so happens that dehumidifiers are sized by their capacity in pints per day. It is important to check these numbers at the peak of the plants’ growth or in the final two weeks of flowering.

A little understanding and a little investigation coupled with a bit of math is all you need to ensure you have the right equipment to protect and grow your investment under all circumstances.


Taking the plunge into cultivation can be a daunting task, there are a lot of variables to consider! Contact one of our cultivation experts today to discuss your project, we'd love to hear from you!

(707)588-8844 [email protected]

Happy Growing!

Information provided by Johnny A/C (articles Rosebud magazine June 2010, Garden & Greenhouses- Thank you for letting us have access to information- information is king and empowers us all)