A sealed room is an indoor garden that is totally … you’ve guessed it … sealed. I’m not just talking about light proofing here. I mean air-sealed. There are no holes, gaps or vents to anything outside of the indoor garden. The aim of the game here is to create a totally controlled environment where every aspect of the plant’s production can be manipulated and customized to produce the optimum results.

Setting up a sealed indoor garden is more expensive but, if done correctly, it should give you the maximum ability to dictate and control temperatures, CO2 levels, humidity, and disease, 24 hours a day, 365 days a year.

Temperature

Now, some of you might be scratching your heads at this point. Isn’t a totally sealed room going to get really, really hot from all the grow lamps? And what’s going to stop the plants from suffocating to death, right? Well, these are the same challenges that face every indoor gardener. It’s just that the “sealed room” approach tackles these challenges in a different way.

First, let’s look at the whole issue of temperature. Every indoor gardener knows that it’s absolutely vital to control this key factor for successful cultivation. Plants perform better in optimum temperature ranges without large fluctuations. So how do we deal with all the heat produced when we fire up our grow lamps, dehumidifiers, pumps and ballasts? The answer is short and simple. AC, my friend! Air Conditioning is the only solution to beat the heat of a sealed room. Here’s an AC rule of thumb to help you spec the right unit:

You will need 4000 BTUs of cooling per 1000 Watts of lighting.

Example: 6 x 1000W= 6000 Total Watts of lighting  x 4000 BTUs= 24,000 BTUs of cooling required.

Note: the term “BTU,” or British Thermal Unit, is used to describe the power of heating and cooling systems. When used as a unit of power, BTU ‘per hour’ (BTU/h, that is, BTU divided by hour) is understood, though this is often abbreviated to just “BTU.”

Be aware that there are companies that have designed units specifically for hydroponic setups that can be installed without the expense of hiring in a certified electrician. These same units can handle the demands of constant cooling year around.

CO2

Next, let’s take a look at CO2 levels. We all know that plants need CO2 in order to photosynthesize, so we’re going to supply this if we’re not relying on fresh air ventilation. Growers using standard ventilation can maintain normal atmospheric levels of CO2 in their indoor gardens. If they wish to add more, however, they often encounter a dilemma. What’s the point of injecting extra CO2 into your indoor growing environment if it’s going to be vented out again before your plants have had a chance to benefit from it? Historically, growers have shut down their ventilation systems temporarily to give their plants time to absorb the extra CO2 but then, of course, temperatures begin to rise! It’s a bit like trying to fit a carpet that’s too big for the room!

With a sealed room you can inject optimum amounts of CO2 without worrying that it’s all being vented away. There are two standard ways to inject CO2 into your environment: using a burner, where natural gas or propane is lit as a flame and the off gas produces CO2; and bottled gas where you open a bottle of CO2, enriching the air directly. Using a burner is most common among larger setups of 6000 watts or more, due to the amount of CO2 required to drive PPMs from 400-2000PPM. This method can create additional heat due to the flame, but keep in mind that using AC can easily combat any heat issues you may have. There are also water-cooled CO2 generators on the market these days. The bottled CO2 is ideal for smaller rooms and can be equipped with diffusers that automatically release the CO2 gas as needed. Many growers have found that having CO2 enriched air in a grow room can produce up to 30% more yield.

Humidity

Next, let’s tackle humidity. Without venting moist air to the outdoors, the humidity in the indoor garden will quickly rise as the plants give off water vapor (transpiration). If humidity levels are too high it can be a cue for pathogens to attack and growth rates to slow dramatically. However, venting presents its own challenges. The outdoors will always dictate the humidity indoors as most places in North America have fairly high levels. In a sealed room you can control humidity to precisely where you want it, all day, every day, using dehumidifiers and air conditioners. Much like air conditioners, dehumidifiers are available in many sizes and properly selecting one for your size room is important. Lower humidity levels are often preferable towards the end of many plants’ flowering cycles to decrease the probability of mold and mildew.

Pests

Finally, a huge advantage of growing in a sealed room is disease and pest control. As long as you make sure you (the grower) stay clean, you can be sure that your environment is sealed from any nasty critters who see your plants as breakfast, lunch or dinner. To explain why a sealed room is ideal for disease control, ask yourself this question: how did my room get diseased in the first place? Much like humans, our environment means everything. It could be large temperature swings, high or low humidity, outside influences such as outdoor crop sprays, insects or anything else floating around. In a sealed room, you not only protect yourself from negative outside influences, but you also strive to create the environment you think is best – independent of what’s going on outdoors.

The sealed room concept has been successfully used for many years in gardens of all sizes.I hope that I’ve managed to inspire thoughts on how to bring a perfect environment to your garden!

Happy growing!